Human cystatin F

ABSTRACT

The invention relates to Cystatin F polypeptides, polynucleotides encoding the polypeptides, methods for producing the polypeptides, in particular by expressing the polynucleotides, and agonists and antagonists of the polypeptides. The invention further relates to methods for utilizing such polynucleotides, polypeptides, agonists and antagonists for applications, which relate, in part, to research, diagnostic and clinical arts.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No. 10/329,428, filed Dec. 27, 2002, which is a divisional of U.S. application Ser. No. 09/528,436, filed Mar. 17, 2000 (now U.S. Pat. No. 6,576,745, issued Jun. 10, 2003), which is a divisional of U.S. application Ser. No. 09/019,485, filed Jan. 29, 1998 (now U.S. Pat. No. 6,066,617, issued May 23, 2000), which is a continuation-in-part of U.S. application Ser. No. 08/832,535, filed Apr. 3, 1997 (now U.S. Pat. No. 5,919,658, issued Jul. 6, 1999), which claims benefit of U.S. Provisional Application No. 60/014,795, filed Apr. 3, 1996. U.S. application Ser. Nos. 09/019,485 and 08/832,535 are each incorporated by reference herein in their entireties.

FIELD OF THE INVENTION

This invention relates, in part, to newly identified polynucleotides and polypeptides; variants and derivatives of the polynucleotides and polypeptides; processes for making the polynucleotides and the polypeptides, and their variants and derivatives; agonists and antagonists of the polypeptides; and uses of the polynucleotides, polypeptides, variants, derivatives, agonists and antagonists. In particular, in these and in other regards, the invention relates to polynucleotides and polypeptides of human Cystatin F.

BACKGROUND OF THE INVENTION

The cystatin super family comprises a group of cysteine proteinase inhibitors which are widely distributed in human tissues and body fluids, and which form tight and reversible complexes with cysteine proteinases such as cathepsins B, H, L, and S. The cystatins are most likely involved in the regulation of normal or pathological processes in which these proteinases participate. Thus, cystatins may influence the intra- and extracellular catabolism of proteins and peptides (Barret, A. J. and Kirchke, H., Methods Enzymol, 80:535-561 (1981)), regulate proteolytic processing of pro-hormones (Orlowski, M., Mol. Cell. Biochem, 52:49-74 (1983)) and pro-enzymes (Taugner, R., et al., Histochemistry, 83:103-108 (1985)), protect against penetration of normal tissues by malignant cells (Sloane, B. F., Semin. Cancer Biol., 1:137-152 (1990)) or microorganisms (Bjorck, L., et al., Nature, 337:385-386 (1989) and Bjorck, L., et al., J. Virol., 64:941-943 (1990)) and modulate local inflammatory processes in rheumatoid arthritis (Mort, J. S., et al., Arthritis Rheum., 27:509-515 (1984)) and purulent bronchiectasis (Buttle, D. J., et al., Scand. J. Clin. Lab. Invest., 50:509-516 (1990)).

The cystatin super family has been sub-divided into families I, II and II (also called the stefin, cystatin and kininogen families, respectively), each with members differing from those of the other families in structural organization and biological distribution (Barret, A. J., et al., Biochem. J., 236:312 (1986)). The family I cystatins A and B are small proteins consisting of single polypeptide chains of about 100 amino acid residues without disulfide bridges. The family II cystatins consists of polypeptide chains of approximately 120 amino acid residues with two intra-chain disulfide bonds. Finally, the family III cystatins, the kininogens, display a higher degree of structural complexity characterized by the presence of three family II cystatin-like domains, each with two disulfide bridges at positions homologous to those in family II cystatins (Muller-Esterl, W., et al., Transbiochem. Sci., 11:336-339 (1986)). Family I and II cystatins are mainly present intracellularly and in secretory fluids (Abrahamson, M., et al., J. Biol. Chem., 261:11282-11289 (1986)), whereas kininogens are highly concentrated in blood plasma (Adam, A., et al., Clin. Chem., 31:423-426 (1985)).

At least one type II cystatin, designated cystatin C, appears to be expressed in all tissues (Abrahamson, M., et al., Biochem. J., 268:287-294 (1990)). In contrast, S-type cystatins are found predominantly in saliva (Abrahamson, M., et al., J. Biol. Chem., 261:11282-11289 (1986)). Cystatins and derivative peptides possess antibacterial and antiviral activities (Bjorck, et al. (1989, 1990)), consistent with their presence in secretions bathing epithelial surfaces directly exposed to the environment. The cystatins may also modulate the immune response. This could occur directly, by inhibiting cysteine proteases releases by macrophages (Bieth, J., Cysteine Proteinases and Their Inhibitors, V. Turk, ed. (Walter De Gruyter & Company, New York) pp. 693-703 (1986)), or indirectly, by inhibiting the chemotaxic response and the phagocytosis-associated respiratory burst of the cells (Leung-Tack, et al., Biol. Chem., 371:255-258 (1990)). This data suggests that type II cystatins might perform a variety of protective functions at epithelial surfaces. The human type II cystatin gene family consists of at least seven members.

The disease hereditary cystatin C amyloid angiopathy (HCCAA) is associated with a Glu→Leu mutation in the gene encoding cystatin C. This leads to deposition of amyloid fibrils comprised of this mutant cystatin C in the cerebral arteries, which appears to cause fatal hemorrhaging (Ghiso, J., et al., PNAS, USA, 83:2974-2978 (1986)).

The effects of cystatin family protease inhibitors are varied and influence numerous functions, both normal and abnormal, in the biological processes of the mammalian system. There is a clear need, therefore, for identification and characterization of proteins that influence biological activity, both normally and in disease states. In particular, there is a need to isolate and characterize additional cystatins akin to known cystatins, which may be employed, therefore, for preventing, ameliorating or correcting dysfunctions or disease or augmenting positive natural actions of such receptors.

SUMMARY OF THE INVENTION

Toward these ends, and others, it is an object of the present invention to provide polypeptides, inter alia, that have been identified as novel Cystatin F by homology between the amino acid sequence set out in FIG. 1 (SEQ ID NO:2) and known amino acid sequences of other proteins such as human cystatin C (SEQ ID NO:3).

It is a further object of the invention, moreover, to provide polynucleotides that encode Cystatin F, particularly polynucleotides that encode the polypeptide herein designated Cystatin F.

In a particularly preferred embodiment of this aspect of the invention the polynucleotide comprises the region encoding human Cystatin F in the sequence set out in FIG. 1 (SEQ ID NO:2).

In accordance with this aspect of the present invention there is provided an isolated nucleic acid molecule encoding a mature polypeptide expressed by the human cDNA contained in ATCC Deposit No. 97463.

In accordance with this aspect of the invention there are provided isolated nucleic acid molecules encoding human Cystatin F, including mRNAs, cDNAs, genomic DNAs and, in further embodiments of this aspect of the invention, biologically, diagnostically, clinically or therapeutically useful variants, analogs or derivatives thereof, or fragments thereof, including fragments of the variants, analogs and derivatives.

Among the particularly preferred embodiments of this aspect of the invention are naturally occurring allelic variants of human Cystatin F.

It also is an object of the invention to provide Cystatin F polypeptides, particularly human Cystatin F polypeptides that may be employed to treat and/or prevent bacterial infection, viral infection, inflammation, protection of the eye and remodeling of the eye. Cystatin F may also be employed to regulate T-cell function and therefore regulate immune responses and may be employed to treat immunological disorders.

In accordance with this aspect of the invention there are provided novel polypeptides of human origin referred to herein as Cystatin F as well as biologically, diagnostically or therapeutically useful fragments, variants and derivatives thereof, variants and derivatives of the fragments, and analogs of the foregoing.

Among the particularly preferred embodiments of this aspect of the invention are variants of human Cystatin F encoded by naturally occurring alleles of the human Cystatin F gene.

It is another object of the invention to provide a process for producing the aforementioned polypeptides, polypeptide fragments, variants and derivatives, fragments of the variants and derivatives, and analogs of the foregoing.

In a preferred embodiment of this aspect of the invention there are provided methods for producing the aforementioned Cystatin F polypeptides comprising culturing host cells having expressibly incorporated therein an exogenously-derived human Cystatin F-encoding polynucleotide under conditions for expression of human Cystatin F in the host and then recovering the expressed polypeptide.

In accordance with another object the invention there are provided products, compositions, processes and methods that utilize the aforementioned polypeptides and polynucleotides for research, biological, clinical and therapeutic purposes, inter alia.

In accordance with certain preferred embodiments of this aspect of the invention, there are provided products, compositions and methods, inter alia, for, among other things: assessing Cystatin F expression in cells by determining Cystatin F polypeptides or Cystatin F-encoding mRNA; assaying genetic variation and aberrations, such as defects, in Cystatin F genes; and administering a Cystatin F polypeptide or polynucleotide to an organism to augment Cystatin F function or remediate Cystatin F dysfunction.

In accordance with certain preferred embodiments of this and other aspects of the invention there are provided probes that hybridize to human Cystatin F sequences.

In certain additional preferred embodiments of this aspect of the invention there are provided antibodies against Cystatin F polypeptides. In certain particularly preferred embodiments in this regard, the antibodies are highly selective for human Cystatin F, which may be employed diagnostically to detect hereditary cystatin C amyloidosis angiopathy (HCCAA) and neoplasia.

In accordance with another aspect of the present invention, there are provided Cystatin F agonists. Among preferred agonists are molecules that mimic Cystatin F, that bind to Cystatin F-binding molecules or receptor molecules, and that elicit or augment Cystatin F-induced responses. Also among preferred agonists are molecules that interact with Cystatin F or Cystatin F polypeptides, or with other modulators of Cystatin F activities, and thereby potentiate or augment an effect of Cystatin F or more than one effect of Cystatin F.

In accordance with yet another aspect of the present invention, there are provided Cystatin F antagonists. Among preferred antagonists are those which mimic Cystatin F so as to bind to Cystatin F receptor or binding molecules but not elicit a Cystatin F-induced response or more than one Cystatin F-induced response. Also among preferred antagonists are molecules that bind to or interact with Cystatin F so as to inhibit an effect of Cystatin F or more than one effect of Cystatin F or which prevent expression of Cystatin F. The antagonists may be used to inhibit the action of Cystatin F polypeptides, for instance, in the treatment and/or prevention of cerebral hemorrhages and encephalopathy and to inhibit HIV infection.

In a further aspect of the invention there are provided compositions comprising a Cystatin F polynucleotide or a Cystatin F polypeptide for administration to cells in vitro, to cells ex vivo and to cells in vivo, or to a multicellular organism. In certain particularly preferred embodiments of this aspect of the invention, the compositions comprise a Cystatin F polynucleotide for expression of a Cystatin F polypeptide in a host organism for treatment of disease. Particularly preferred in this regard is expression in a human patient for treatment of a dysfunction associated with aberrant endogenous activity of Cystatin F.

Other objects, features, advantages and aspects of the present invention will become apparent to those of skill from the following description. It should be understood, however, that the following description and the specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only. Various changes and modifications within the spirit and scope of the disclosed invention will become readily apparent to those skilled in the art from reading the following description and from reading the other parts of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings depict certain embodiments of the invention. They are illustrative only and do not limit the invention otherwise disclosed herein.

FIG. 1 illustrates the nucleotide (SEQ ID NO:1) and deduced amino acid sequence (SEQ ID NO:2) of human Cystatin F. The observed leader sequence of about 19 amino acids is underlined. Note that the methionine residue at the beginning of the leader sequence in FIG. 1 is shown in position number (positive) 1, whereas the leader positions in the corresponding sequence of SEQ ID NO:2 and in the corresponding translated sequence of SEQ ID NO:1 are designated with negative position numbers. Thus, the leader sequence positions 1 to 19 in FIG. 1 correspond to positions −19 to −1 in SEQ ID NO:2 and in the corresponding translated sequence of SEQ ID NO:1.

Residues involved in enzyme binding for other cystatins are boxed. The asparagine residue of two theoretical asparagine-linked glycosylation sites (N-X-S or N-X-T) are marked with a bolded N(N) in the amino acid sequence and a bolded pound sign (#) above the nucleotide codon encoding the asparagine residue.

FIG. 2 shows the regions of identity between the amino acid sequences of the Cystatin F protein (SEQ ID NO:2) and translation product of the human mRNA for Cystatin C (SEQ ID NO:3), determined by the computer program Bestfit (Wisconsin Sequence Analysis Package, Version 8 for Unix, Genetics Computer Group, University Research Park, 575 Science Drive, Madison, Wis. 53711) using the default parameters.

FIG. 3 shows an analysis of the Cystatin F amino acid sequence. Alpha, beta, turn and coil regions; hydrophilicity and hydrophobicity; amphipathic regions; flexible regions; antigenic index and surface probability are shown. In the “Antigenic Index or Jameson-Wolf” graph, the positive peaks indicate locations of the highly antigenic regions of the Cystatin F protein, i.e., regions from which epitope-bearing peptides of the invention can be obtained.

FIG. 4 illustrates the results of a time-course experiment for deglycosylation of recombinant Cystatin F by incubation with PNGase F. Samples were electrophoretically separated by SDS-PAGE in a 16.5% polyacrylamide gel. The gel was analyzed by silver staining. Lane 1 contains isolated recombinant Cystatin F, with no PNGase F added. Lanes 2 through 6 show the same Cystatin F incubated with PNGase F at 37 degrees C. for 30 seconds (lane 2), 30 minutes (lane 3), 1 hour (lane 4), 3 hours (lane 5), and 6 hours (lane 6). The sizes of relevant molecular mass markers are shown to the left.

FIG. 5 illustrates the presence of a protein with immunoreactivity and size as recombinant Cystatin F is present in human blood and lymphoid cells. Recombinant Cystatin F and native human Cystatin F produced by U-937 cells were analyzed by using a Superdex 75 column to perform gel filtration. Spent medium from serum-free cultures of U-937 cells (100 mL) was concentrated 200 times by ultrafiltration and applied to the column. Cystatin F content in the fractions was measured by ELISA and is represented in the figure by the dashed line. Approximately 0.3 mg of isolated recombinant Cystatin F was gel filtered using the same protocol and is represented in the figure by the solid line. The peak fractions for gel filtration of isolated recombinant cystatin C and the arrows indicate cystatin E/M on the same column under identical conditions.

FIG. 6 illustrates the expression pattern of Cystatin F in human tissues by Northern analysis. Northern blots containing electrophoretically separated samples of 2 μg of poly A+ RNA isolated from various human tissues (the blots were obtained from CLONETECH) were hybridized to the full-length Cystatin F cDNA clone HCUDE60. The positions of the molecular mass standards are indicated in the figure. PBL is an abbreviation for peripheral blood leukocytes.

GLOSSARY

The following illustrative explanations are provided to facilitate understanding of certain terms used frequently herein, particularly in the examples. The explanations are provided as a convenience and are not limitative of the invention.

DIGESTION of DNA refers to catalytic cleavage of the DNA with a restriction enzyme that acts only at certain sequences in the DNA. The various restriction enzymes referred to herein are commercially available and their reaction conditions, cofactors and other requirements for use are known and routine to the skilled artisan.

For analytical purposes, typically, 1 mg of plasmid or DNA fragment is digested with about 2 units of enzyme in about 20 ml of reaction buffer. For isolating DNA fragments for plasmid construction, typically 5 to 50 mg of DNA is digested with 20 to 250 units of enzyme in proportionately larger volumes.

Appropriate buffers and substrate amounts for particular restriction enzymes are described in standard laboratory manuals, such as those referenced below, and they are specified by commercial suppliers.

Incubation times of about 1 hour at 37 degrees C. are ordinarily used, but conditions may vary in accordance with standard procedures, the supplier's instructions and the particulars of the reaction. After digestion, reactions may be analyzed, and fragments may be purified by electrophoresis through an agarose or polyacrylamide gel, using well-known methods that are routine for those skilled in the art.

GENETIC ELEMENT generally means a polynucleotide comprising a region that encodes a polypeptide or a region that regulates transcription or translation or other processes important to expression of the polypeptide in a host cell, or a polynucleotide comprising both a region that encodes a polypeptide and a region operably linked thereto that regulates expression.

Genetic elements may be comprised within a vector that replicates as an episomal element; that is, as a molecule physically independent of the host cell genome. They may be comprised within mini-chromosomes, such as those that arise during amplification of transfected DNA by methotrexate selection in eukaryotic cells. Genetic elements also may be comprised within a host cell genome; not in their natural state but, rather, following manipulation such as isolation, cloning and introduction into a host cell in the form of purified DNA or in a vector, among others.

ISOLATED means altered “by the hand of man” from its natural state; i.e., that, if it occurs in nature, it has been changed or removed from its original environment, or both.

For example, a naturally occurring polynucleotide or a polypeptide naturally present in a living animal in its natural state is not “isolated,” but the same polynucleotide or polypeptide separated from the coexisting materials of its natural state is “isolated”, as the term is employed herein. For example, with respect to polynucleotides, the term isolated means that it is separated from the chromosome and cell in which it naturally occurs.

As part of or following isolation, such polynucleotides can be joined to other polynucleotides, such as DNAs, for mutagenesis, to form fusion proteins, and for propagation or expression in a host, for instance. The isolated polynucleotides, alone or joined to other polynucleotides such as vectors, can be introduced into host cells, in culture or in whole organisms. Introduced into host cells in culture or in whole organisms, such DNAs still would be isolated, as the term is used herein, because they would not be in their naturally occurring form or environment. Similarly, the polynucleotides and polypeptides may occur in a composition, such as a media formulations, solutions for introduction of polynucleotides or polypeptides, for example, into cells, compositions or solutions for chemical or enzymatic reactions, for instance, which are not naturally occurring compositions, and, therein remain isolated polynucleotides or polypeptides within the meaning of that term as it is employed herein.

LIGATION refers to the process of forming phosphodiester bonds between two or more polynucleotides, which most often are double stranded DNAs. Techniques for ligation are well known to the art and protocols for ligation are described in standard laboratory manuals and references, such as, for instance, Sambrook et al., MOLECULAR CLONING, A LABORATORY MANUAL, 2nd Ed.; Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. (1989) and Maniatis et al., pg. 146, as cited below.

OLIGONUCLEOTIDE(S) refers to relatively short polynucleotides. Often the term refers to single-stranded deoxyribonucleotides, but it can refer as well to single-or double-stranded ribonucleotides, RNA:DNA hybrids and double-stranded DNAs, among others.

Oligonucleotides, such as single-stranded DNA probe oligonucleotides, often are synthesized by chemical methods, such as those implemented on automated oligonucleotide synthesizers. However, oligonucleotides can be made by a variety of other methods, including in vitro recombinant DNA-mediated techniques and by expression of DNAs in cells and organisms.

Initially, chemically synthesized DNAs typically are obtained without a 5′ phosphate. The 5′ ends of such oligonucleotides are not substrates for phosphodiester bond formation by ligation reactions that employ DNA ligases typically used to form recombinant DNA molecules. Where ligation of such oligonucleotides is desired, a phosphate can be added by standard techniques, such as those that employ a kinase and ATP.

The 3′ end of a chemically synthesized oligonucleotide generally has a free hydroxyl group and, in the presence of a ligase, such as T4 DNA ligase, readily will form a phosphodiester bond with a 5′ phosphate of another polynucleotide, such as another oligonucleotide. As is well known, this reaction can be prevented selectively, where desired, by removing the 5′ phosphates of the other polynucleotide(s) prior to ligation.

PLASMIDS generally are designated herein by a lower case p preceded and/or followed by capital letters and/or numbers, in accordance with standard naming conventions that are familiar to those of skill in the art.

Starting plasmids disclosed herein are either commercially available, publicly available on an unrestricted basis, or can be constructed from available plasmids by routine application of well-known, published procedures. Many plasmids and other cloning and expression vectors that can be used in accordance with the present invention are well known and readily available to those of skill in the art. Moreover, those of skill readily may construct any number of other plasmids suitable for use in the invention. The properties, construction and use of such plasmids, as well as other vectors, in the present invention will be readily apparent to those of skill from the present disclosure.

POLYNUCLEOTIDE(S) generally refers to any polyribonucleotide or polydeoxribonucleotide, which may be unmodified RNA or DNA or modified RNA or DNA. Thus, for instance, polynucleotides as used herein refers to, among others, single- and double-stranded DNA, DNA that is a mixture of single- and double-stranded regions, single- and double-stranded RNA, and RNA that is mixture of single- and double-stranded regions, hybrid molecules comprising DNA and RNA that may be single-stranded or, more typically, double-stranded or a mixture of single- and double-stranded regions.

In addition, polynucleotide as used herein refers to triple-stranded regions comprising RNA or DNA or both RNA and DNA. The strands in such regions may be from the same molecule or from different molecules. The regions may include all of one or more of the molecules, but more typically involve only a region of some of the molecules. One of the molecules of a triple-helical region often is an oligonucleotide.

As used herein, the term polynucleotide includes DNAs or RNAs as described above that contain one or more modified bases. Thus, DNAs or RNAs with backbones modified for stability or for other reasons are “polynucleotides” as that term is intended herein. Moreover, DNAs or RNAs comprising unusual bases, such as inosine, or modified bases, such as tritylated bases, to name just two examples, are polynucleotides as the term is used herein.

It will be appreciated that a great variety of modifications have been made to DNA and RNA that serve many useful purposes known to those of skill in the art. The term polynucleotide as it is employed herein embraces such chemically, enzymatically or metabolically modified forms of polynucleotides, as well as the chemical forms of DNA and RNA characteristic of viruses and cells, including simple and complex cells, inter alia.

POLYPEPTIDE, as used herein, includes all polypeptides as described below. The basic structure of polypeptides is well known and has been described in innumerable textbooks and other publications in the art. In this context, the term is used herein to refer to any peptide or protein comprising two or more amino acids joined to each other in a linear chain by peptide bonds. As used herein, the term refers to both short chains, which also commonly are referred to in the art as peptides, oligopeptides and oligomers, for example, and to longer chains, which generally are referred to in the art as proteins, of which there are many types.

It will be appreciated that polypeptides often contain amino acids other than the 20 amino acids commonly referred to as the 20 naturally occurring amino acids, and that many amino acids, including the terminal amino acids, may be modified in a given polypeptide, either by natural processes, such as processing and other post-translational modifications, but also by chemical modification techniques which are well known to the art. Even the common modifications that occur naturally in polypeptides are too numerous to list exhaustively here, but they are well described in basic texts and in more detailed monographs, as well as in a voluminous research literature, and they are well known to those of skill in the art.

Among the known modifications which may be present in polypeptides of the present are, to name an illustrative few, acetylation, acylation, ADP-ribosylation, amidation, covalent attachment of flavin, covalent attachment of a heme moiety, covalent attachment of a nucleotide or nucleotide derivative, covalent attachment of a lipid or lipid derivative, covalent attachment of phosphotidylinositol, cross-linking, cyclization, disulfide bond formation, demethylation, formation of covalent cross-links, formation of cysteine, formation of pyroglutamate, formylation, gamma-carboxylation, glycosylation, GPI anchor formation, hydroxylation, iodination, methylation, myristoylation, oxidation, proteolytic processing, phosphorylation, prenylation, racemization, selenoylation, sulfation, transfer-RNA mediated addition of amino acids to proteins such as arginylation, and ubiquitination.

Such modifications are well known to those of skill and have been described in great detail in the scientific literature. Several particularly common modifications, glycosylation, lipid attachment, sulfation, gamma-carboxylation of glutamic acid residues, hydroxylation and ADP-ribosylation, for instance, are described in most basic texts, such as, for instance PROTEINS—STRUCTURE AND MOLECULAR PROPERTIES, 2nd Ed., T. E. Creighton, W.H. Freeman and Company, New York (1993). Many detailed reviews are available on this subject, such as, for example, those provided by Wold, F., Posttranslational Protein Modifications: Perspectives and Prospects, pgs. 1-12 in POSTTRANSLATIONAL COVALENT MODIFICATION OF PROTEINS, B. C. Johnson, Ed., Academic Press, New York (1983); Seifter et al., Analysis for protein modifications and nonprotein cofactors, Meth. Enzymol. 182: 626-646 (1990) and Rattan et al., Protein Synthesis: Posttranslational Modifications and Aging, Ann. N.Y. Acad. Sci. 663: 48-62 (1992).

It will be appreciated, as is well known and as noted above, that polypeptides are not always entirely linear. For instance, polypeptides may be branched as a result of ubiquitination, and they may be circular, with or without branching, generally as a result of post translation events, including natural processing event and events brought about by human manipulation which do not occur naturally. Circular, branched and branched circular polypeptides may be synthesized by non-translation natural process and by entirely synthetic methods, as well.

Modifications can occur anywhere in a polypeptide, including the peptide backbone, the amino acid side-chains and the amino or carboxyl termini. In fact, blockage of the amino or carboxyl group in a polypeptide, or both, by a covalent modification, is common in naturally occurring and synthetic polypeptides and such modifications may be present in polypeptides of the present invention, as well. For instance, the amino terminal residue of polypeptides made in E. coli, prior to proteolytic processing, almost invariably will be N-formylmethionine.

The modifications that occur in a polypeptide often will be a function of how it is made. For polypeptides made by expressing a cloned gene in a host, for instance, the nature and extent of the modifications in large part will be determined by the host cell posttranslational modification capacity and the modification signals present in the polypeptide amino acid sequence. For instance, as is well known, glycosylation often does not occur in bacterial hosts such as E. coli. Accordingly, when glycosylation is desired, a polypeptide should be expressed in a glycosylating host, generally a eukaryotic cell. Insect cell often carry out the same posttranslational glycosylations as mammalian cells and, for this reason, insect cell expression systems have been developed to express efficiently mammalian proteins having native patterns of glycosylation, inter alia. Similar considerations apply to other modifications.

It will be appreciated that the same type of modification may be present in the same or varying degree at several sites in a given polypeptide. Also, a given polypeptide may contain many types of modifications.

In general, as used herein, the term polypeptide encompasses all such modifications, particularly those that are present in polypeptides synthesized by expressing a polynucleotide in a host cell.

VARIANT(S) of polynucleotides or polypeptides, as the term is used herein, are polynucleotides or polypeptides that differ from a reference polynucleotide or polypeptide, respectively. Variants in this sense are described below and elsewhere in the present disclosure in greater detail.

A polynucleotide that differs in nucleotide sequence from another, reference polynucleotide. Generally, differences are limited so that the nucleotide sequences of the reference and the variant are closely similar overall and, in many regions, identical.

As noted below, changes in the nucleotide sequence of the variant may be silent. That is, they may not alter the amino acids encoded by the polynucleotide. Where alterations are limited to silent changes of this type a variant will encode a polypeptide with the same amino acid sequence as the reference. Also as noted below, changes in the nucleotide sequence of the variant may alter the amino acid sequence of a polypeptide encoded by the reference polynucleotide. Such nucleotide changes may result in amino acid substitutions, additions, deletions, fusions and truncations in the polypeptide encoded by the reference sequence, as discussed below.

A polypeptide that differs in amino acid sequence from another, reference polypeptide. Generally, differences are limited so that the sequences of the reference and the variant are closely similar overall and, in many regions, identical.

A variant and reference polypeptide may differ in amino acid sequence by one or more substitutions, additions, deletions, fusions and truncations, which may be present in any combination.

RECEPTOR MOLECULE, as used herein, refers to molecules which bind or interact specifically with Cystatin F polypeptides of the present invention, including not only classic receptors, which are preferred, but also other molecules that specifically bind to or interact with polypeptides of the invention (which also may be referred to as “binding molecules” and “interaction molecules,” respectively and as “Cystatin F binding molecules” and “Cystatin F interaction molecules.” Binding between polypeptides of the invention and such molecules, including receptor or binding or interaction molecules may be exclusive to polypeptides of the invention, which is very highly preferred, or it may be highly specific for polypeptides of the invention, which is highly preferred, or it may be highly specific to a group of proteins that includes polypeptides of the invention, which is preferred, or it may be specific to several groups of proteins at least one of which includes polypeptides of the invention.

Receptors also may be non-naturally occurring, such as antibodies and antibody-derived reagents that bind specifically to polypeptides of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to novel Cystatin F polypeptides and polynucleotides, among other things, as described in greater detail below. In particular, the invention relates to polypeptides and polynucleotides of a novel human Cystatin F, which is related by amino acid sequence homology to human Cystatin F. The invention relates especially to Cystatin F having the nucleotide and amino acid sequences set out in FIG. 1 (SEQ ID NO:1 and 2), and to the Cystatin F nucleotide and amino acid sequences of the human cDNA in ATCC Deposit No. 97463 which is herein referred to as “the deposited clone” or as the “cDNA of the deposited clone.” It will be appreciated that the nucleotide and amino acid sequences set out in FIG. 1 (SEQ ID NO:2) were obtained by sequencing the human cDNA of the deposited clone. Hence, the sequence of the deposited clone is controlling as to any discrepancies between the two and any reference to the sequence of FIG. 1 (SEQ ID NO:1) includes reference to the sequence of the human cDNA of the deposited clone.

Polynucleotides

In accordance with one aspect of the present invention, there are provided isolated polynucleotides that encode the Cystatin F polypeptide having the deduced amino acid sequence of FIG. 1 (SEQ ID NO:2).

Using the information provided herein, such as the polynucleotide sequence set out in FIG. 1 (SEQ ID NO:1), a polynucleotide of the present invention encoding a human Cystatin F polypeptide may be obtained using standard cloning and screening procedures, such as those for cloning cDNAs using mRNA from cells of human tissue as starting material. Illustrative of the invention, the polynucleotide set out in FIG. 1 (SEQ ID NO:1) was discovered in a cDNA library derived from cells of a human cord-blood CD34 deleted buffy coat.

Human Cystatin F of the invention is structurally related to other proteins of the cystatin family, as shown by the results of sequencing the human cDNA encoding human Cystatin F in the deposited clone. The human cDNA sequence thus obtained is set out in FIG. 1 (SEQ ID NO:1). It contains an open reading frame encoding a protein of about 145 amino acid residues, with a predicted leader portion of 19 amino acids, a deduced molecular weight of about 16.5 kDa, an isoelectric point of 8.481 and a 5.336 charge at pH of 7.0. Expression in insect cells (Example 2, below) produced a mature protein with an N-terminal amino acid sequence beginning at amino acid 20 in FIG. 1 (SEQ ID NO:2), indicating a correct prediction of the leader portion of 19 amino acids. The protein exhibits greatest homology to human cystatin C among known proteins. The residues of the Cystatin F of FIG. 1 (SEQ ID NO:2) have about 34% identity and about 41% similarity with the amino acid sequence of human cystatin C (FIG. 2).

Using the information provided herein, such as the nucleotide sequence in FIG. 1 (SEQ ID NO:1), a nucleic acid molecule of the present invention encoding a Cystatin F polypeptide may be obtained using standard cloning and screening procedures, such as those for cloning cDNAs using mRNA as starting material. Illustrative of the invention, the nucleic acid molecule described in FIG. 1 (SEQ ID NO:1) was discovered in a cDNA library derived from a CD34-depleted Buffy Coat.

Additional clones of the same gene were also identified in cDNA libraries from the following sources: primary dendritic cells, bone marrow, anergic T-cells, membrane-bound polysomes isolated from Jurkat cells, apoptotic T-cells, resting HL-60 cells, T-helper cells, osteosarcoma, peripheral blood mononuclear cells stimulated with poly[I-C], and pancreatic islet cell tumor.

Polynucleotides of the present invention may be in the form of RNA, such as mRNA, or in the form of DNA, including, for instance, cDNA and genomic DNA obtained by cloning or produced by chemical synthetic techniques or by a combination thereof. The DNA may be double-stranded or single-stranded. Single-stranded DNA may be the coding strand, also known as the sense strand, or it may be the non-coding strand, also referred to as the anti-sense strand.

The coding sequence that encodes the polypeptide may be identical to the coding sequence of the polynucleotide shown in FIG. 1 (SEQ ID NO:1). It also may be a polynucleotide with a different sequence, which, as a result of the redundancy (degeneracy) of the genetic code, encodes the polypeptide of the DNA of FIG. 1 (SEQ ID NO:1).

The amino acid sequence of the complete Cystatin F protein includes a leader sequence and a mature protein, as shown in SEQ ID NO:2. More in particular, the present invention provides nucleic acid molecules encoding a mature form of the Cystatin F protein. Thus, according to the signal hypothesis, once export of the growing protein chain across the rough endoplasmic reticulum has been initiated, proteins secreted by mammalian cells have a signal or secretory leader sequence which is cleaved from the complete polypeptide to produce a secreted “mature” form of the protein. Most mammalian cells and even insect cells cleave secreted proteins with the same specificity. However, in some cases, cleavage of a secreted protein is not entirely uniform, which results in two or more mature species of the protein. Further, it has long been known that the cleavage specificity of a secreted protein is ultimately determined by the primary structure of the complete protein, that is, it is inherent in the amino acid sequence of the polypeptide. Therefore, the present invention provides a nucleotide sequence encoding the mature Cystatin F polypeptide having the amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 97463. By the “mature Cystatin F polypeptide having the amino acid sequence encoded by the cDNA clone in ATCC Deposit No. 97463” is meant the mature form(s) of the Cystatin F protein produced by expression in a mammalian cell (e.g., COS cells, as described below) of the complete open reading frame encoded by the human DNA sequence of the deposited clone.

In addition, methods for predicting whether a protein has a secretory leader as well as the cleavage point for that leader sequence are available. For instance, the method of McGeoch (Virus Res. 3:271-286 (1985)) uses the information from a short N-terminal charged region and a subsequent uncharged region of the complete (uncleaved) protein. The method of von Heinje (Nucleic Acids Res. 14:4683-4690 (1986)) uses the information from the residues surrounding the cleavage site, typically residues −13 to +2 where +1 indicates the amino terminus of the mature protein. The accuracy of predicting the cleavage points of known mammalian secretory proteins for each of these methods is in the range of 75-80% (von Heinje, supra). However, the two methods do not always produce the same predicted cleavage point(s) for a given protein.

In the present case, the deduced amino acid sequence of the complete Cystatin F polypeptide was analyzed by a computer program “PSORT”, available from Dr. Kenta Nakai of the Institute for Chemical Research, Kyoto University (Nakai, K. and Kanehisa, M. Genomics 14:897-911 (1992)), which is an expert system for predicting the cellular location of a protein based on the amino acid sequence. As part of this computational prediction of localization, the methods of McGeoch and von Heinje are incorporated. Thus, the computation analysis above predicted a single cleavage site, between amino acids 19 and 20, within the complete amino acid sequence shown in FIG. 1.

Thus, one aspect of the invention provides an isolated nucleic acid molecule comprising a polynucleotide having a nucleotide sequence selected from the group consisting of: (a) a nucleotide sequence encoding the Cystatin F polypeptide having the complete amino acid sequence in SEQ ID NO:2 (i.e., positions −19 to 126 of SEQ ID NO:2); (b) a nucleotide sequence encoding the Cystatin F polypeptide having the complete amino acid sequence in SEQ ID NO:2 excepting the N-terminal methionine (i.e., positions −18 to 126 of SEQ ID NO:2); (c) a nucleotide sequence encoding the predicted mature Cystatin F polypeptide having the amino acid sequence at positions +1 to 126 in SEQ ID NO:2; (d) a nucleotide sequence encoding the Cystatin F polypeptide having the complete amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 97463; (e) a nucleotide sequence encoding the Cystatin F polypeptide having the complete amino acid sequence excepting the N-terminal methionine encoded by the cDNA clone contained in ATCC Deposit No. 97463; (f) a nucleotide sequence encoding the mature Cystatin F polypeptide having the amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 97463; and (g) a nucleotide sequence complementary to any of the nucleotide sequences in (a), (b), (c), (d), (e) or (f), above.

Polynucleotides of the present invention which encode the polypeptide of FIG. 1 (SEQ ID NO:2) may include, but are not limited to the coding sequence for the mature polypeptide, by itself; the coding sequence for the mature polypeptide and additional coding sequences, such as those encoding a leader or secretory sequence, such as a pre-, or pro- or prepro-protein sequence; the coding sequence of the mature polypeptide, with or without the aforementioned additional coding sequences, together with additional, non-coding sequences, including for example, but not limited to introns and non-coding 5′ and 3′ sequences, such as the transcribed, non-translated sequences that play a role in transcription, mRNA processing—including splicing and polyadenylation signals, for example—ribosome binding and stability of mRNA; additional coding sequence which codes for additional amino acids, such as those which provide additional functionalities. Thus, for instance, the polypeptide may be fused to a marker sequence, such as a peptide, which facilitates purification of the fused polypeptide. In certain preferred embodiments of this aspect of the invention, the marker sequence is a hexa-histidine peptide, such as the tag provided in a pQE vector (Qiagen, Inc.), among others, many of which are commercially available. As described in Gentz et al., Proc. Natl. Acad. Sci., USA 86: 821-824 (1989), for instance, hexa-histidine provides for convenient purification of the fusion protein.

The HA tag corresponds to an epitope derived of influenza hemagglutinin protein, which has been described by Wilson et al., Cell 37: 767 (1984), for instance.

In accordance with the foregoing, the term “polynucleotide encoding a polypeptide” as used herein encompasses polynucleotides that include a sequence encoding a polypeptide of the present invention, particularly the human Cystatin F having the amino acid sequence set out in FIG. 1 (SEQ ID NO:2). The term encompasses polynucleotides that include a single continuous region or discontinuous regions encoding the polypeptide (for example, interrupted by introns) together with additional regions.

The present invention further relates to variants of the herein above described polynucleotides, which encode for fragments, analogs, and derivatives of the polypeptide having the deduced amino acid sequence of FIG. 1 (SEQ ID NO:2). A variant of the polynucleotide may be a naturally occurring variant such as a naturally occurring allelic variant, or it may be a variant that is not known to occur naturally. Such non-naturally occurring variants of the polynucleotide may be made by mutagenesis techniques, including those applied to polynucleotides, cells, or organisms.

Among variants in this regard are variants that differ from the aforementioned polynucleotides by nucleotide substitutions, deletions or additions. The substitutions, deletions, or additions may involve one or more nucleotides. The variants may be altered in coding or non-coding regions or both. Alterations in the coding regions may produce conservative or non-conservative amino acid substitutions, deletions, or additions.

Among the particularly preferred embodiments of the invention in this regard are polynucleotides encoding polypeptides having the amino acid sequence of Cystatin F set out in FIG. 1 (SEQ ID NO:2); variants, analogs, derivatives and fragments thereof, and fragments of the variants, analogs and derivatives.

Further particularly preferred in this regard are polynucleotides encoding Cystatin F variants, analogs, derivatives and fragments, and variants, analogs and derivatives of the fragments, which have the amino acid sequence of the Cystatin F polypeptide of FIG. 1 (SEQ ID NO:2) in which several, a few, 5 to 10, 1 to 5, 1 to 3, 2, 1 or no amino acid residues are substituted, deleted or added, in any combination. Especially preferred among these are silent substitutions, additions and deletions, which do not alter the properties and activities of the Cystatin F. Also especially preferred in this regard are conservative substitutions. Most highly preferred are polynucleotides encoding polypeptides having the amino acid sequence of FIG. 1 (SEQ ID NO:2) without substitutions.

Further preferred embodiments of the invention are polynucleotides that are at least 70% identical to a polynucleotide encoding the Cystatin F polypeptide having the amino acid sequence set out in FIG. 1 (SEQ ID NO:2), and polynucleotides that are complementary to such polynucleotides. Alternatively, most highly preferred are polynucleotides that comprise a region that is at least 80% identical to a polynucleotide encoding the Cystatin F polypeptide and polynucleotides complementary thereto. In this regard, polynucleotides at least 90% identical to the same are particularly preferred, and among these particularly preferred polynucleotides, those with at least 95% are especially preferred. Furthermore, those with at least 97% are highly preferred among those with at least 95%, and among these those with at least 98% and at least 99% are particularly highly preferred, with at least 99% being the more preferred.

By a polynucleotide having a nucleotide sequence at least, for example, 95% “identical” to a reference nucleotide sequence encoding a Cystatin F polypeptide is intended that the nucleotide sequence of the polynucleotide is identical to the reference sequence except that the polynucleotide sequence may include up to five point mutations per each 100 nucleotides of the reference nucleotide sequence encoding the Cystatin F polypeptide. In other words, to obtain a polynucleotide having a nucleotide sequence at least 95% identical to a reference nucleotide sequence, up to 5% of the nucleotides in the reference sequence may be deleted or substituted with another nucleotide, or a number of nucleotides up to 5% of the total nucleotides in the reference sequence may be inserted into the reference sequence while retaining substantially all biological activity. These mutations of the reference sequence may occur at the 5′ or 3′ terminal positions of the reference nucleotide sequence or anywhere between those terminal positions, interspersed either individually among nucleotides in the reference sequence or in one or more contiguous groups within the reference sequence.

As a practical matter, whether any particular nucleic acid molecule is at least 90%, 95%, 96%, 97%, 98% or 99% identical to, for instance, the nucleotide sequence shown in FIG. 1 or to the nucleotides sequence of the deposited cDNA clone can be determined conventionally using known computer programs such as the Bestfit program (Wisconsin Sequence Analysis Package, Version 8 for Unix, Genetics Computer Group, University Research Park, 575 Science Drive, Madison, Wis. 53711). Bestfit uses the local homology algorithm of Smith and Waterman to find the best segment of homology between two sequences (Advances in Applied Mathematics 2:482-489 (1981)). When using Bestfit or any other sequence alignment program to determine whether a particular sequence is, for instance, 95% identical to a reference sequence according to the present invention, the parameters are set, of course, such that the percentage of identity is calculated over the full length of the reference nucleotide sequence and that gaps in homology of up to 5% of the total number of nucleotides in the reference sequence are allowed.

The present application is directed to nucleic acid molecules at least 90%, 95%, 96%, 97%, 98% or 99% identical to the nucleic acid sequence shown in FIG. 1 (SEQ ID NO:1) or to the nucleic acid sequence of the deposited cDNA, irrespective of whether they encode a polypeptide having Cystatin F activity. This is because even where a particular nucleic acid molecule does not encode a polypeptide having Cystatin F activity, one of skill in the art would still know how to use the nucleic acid molecule, for instance, as a hybridization probe or a polymerase chain reaction (PCR) primer. Uses of the nucleic acid molecules of the present invention that do not encode a polypeptide having Cystatin F activity include, inter alia, (1) isolating the Cystatin F gene or allelic variants thereof in a cDNA library; (2) in situ hybridization (e.g., “FISH”) to metaphase chromosomal spreads to provide precise chromosomal location of the Cystatin F gene, as described by Verma and colleagues (Human Chromosomes: A Manual of Basic Techniques, Pergamon Press, New York (1988)); and Northern Blot analysis for detecting Cystatin F mRNA expression in specific tissues.

Preferred, however, are nucleic acid molecules having sequences at least 90%, 95%, 96%, 97%, 98% or 99% identical to the nucleic acid sequence shown in FIG. 1 (SEQ ID NO:1) or to the nucleic acid sequence of the deposited cDNA which do, in fact, encode a polypeptide having Cystatin F protein activity. By “a polypeptide having Cystatin F activity” are intended polypeptides exhibiting activity similar, but not necessarily identical, to an activity of the mature Cystatin F protein of the invention, as measured in a particular biological assay.

Of course, due to the degeneracy of the genetic code, one of ordinary skill in the art will immediately recognize that a large number of the nucleic acid molecules having a sequence at least 90%, 95%, 96%, 97%, 98%, or 99% identical to the nucleic acid sequence of the deposited cDNA or the nucleic acid sequence shown in FIG. 1 (SEQ ID NO:1) will encode a polypeptide “having Cystatin F protein activity.” In fact, since degenerate variants of these nucleotide sequences all encode the same polypeptide, this will be clear to the skilled artisan even without performing the above described comparison assay. It will be further recognized in the art that, for such nucleic acid molecules that are not degenerate variants, a reasonable number will also encode a polypeptide having Cystatin F protein activity. This is because the skilled artisan is fully aware of amino acid substitutions that are either less likely or not likely to significantly effect protein function (e.g., replacing one aliphatic amino acid with a second aliphatic amino acid), as further described below.

Particularly preferred embodiments in this respect, moreover, are polynucleotides that encode polypeptides that retain substantially the same biological function or activity as the mature polypeptide encoded by the human cDNA of FIG. 1 (SEQ ID NO:1).

The present invention further relates to polynucleotides that hybridize to the herein above-described sequences. In this regard, the present invention especially relates to polynucleotides that hybridize under stringent conditions to the herein above-described polynucleotides. As herein used, the term “stringent conditions” means hybridization will occur only if there is at least 95% and preferably at least 97% identity between the sequences.

As discussed additionally herein regarding polynucleotide assays of the invention, for instance, polynucleotides of the invention as discussed above, may be used as a hybridization probe for cDNA and genomic DNA to isolate full-length cDNAs and genomic clones encoding Cystatin F and to isolate cDNA and genomic clones of other genes that have a high sequence similarity to the human Cystatin F gene. Such probes generally will comprise at least 15 bases. Preferably, such probes will have at least 30 bases and may have at least 50 bases. Particularly preferred probes will have at least 30 bases and will have 50 bases or less.

For example, the coding region of the Cystatin F gene may be isolated by screening using the known DNA sequence to synthesize an oligonucleotide probe. A labeled oligonucleotide having a sequence complementary to that of a gene of the present invention is then used to screen a library of human cDNA, genomic DNA or mRNA to determine to which members of the library the probe hybridizes.

The present invention is further directed to nucleic acid molecules encoding portions of the nucleotide sequences described herein as well as to fragments of the isolated nucleic acid molecules described herein. In particular, the invention provides a polynucleotide having a nucleotide sequence representing the portion of SEQ ID NO:1 that consists of positions 1-633 of SEQ ID NO:1. Further, the invention includes a polynucleotide comprising any portion of at least about 30 nucleotides, preferably at least about 50 nucleotides, of SEQ ID NO:1 from positions 1-633 of SEQ ID NO:1, excluding the sequences of the following related cDNA clones, and any subfragments therein: HOAAF73R (SEQ ID NO:4), HLMCM30R (SEQ ID NO:5), HTXBK59R (SEQ ID NO:6), N56875 (SEQ ID NO:7), and N47763 (SEQ ID NO:8).

The polynucleotides and polypeptides of the present invention may be employed as research reagents and materials for discovery of treatments and diagnostics to human disease, as further discussed herein relating to polynucleotide assays, inter alia.

The polynucleotides may encode a polypeptide that is the mature protein plus additional amino or carboxyl-terminal amino acids, or amino acids interior to the mature polypeptide (when the mature form has more than one polypeptide chain, for instance). Such sequences may play a role in processing of a protein from precursor to a mature form, may facilitate protein trafficking, may prolong or shorten protein half-life or may facilitate manipulation of a protein for assay or production, among other things. As generally is the case in situ, the additional amino acids may be processed away from the mature protein by cellular enzymes.

A precursor protein, having the mature form of the polypeptide fused to one or more prosequences may be an inactive form of the polypeptide. When prosequences are removed such inactive precursors generally are activated. Some or all of the prosequences may be removed before activation. Generally, such precursors are called proproteins.

In sum, a polynucleotide of the present invention may encode a mature protein, a mature protein plus a leader sequence (which may be referred to as a preprotein), a precursor of a mature protein having one or more prosequences which are not the leader sequences of a preprotein, or a preproprotein, which is a precursor to a proprotein, having a leader sequence and one or more prosequences, which generally are removed during processing steps that produce active and mature forms of the polypeptide.

Deposited Materials

A deposit containing a human Cystatin F cDNA has been deposited with the American Type Culture Collection, as noted above. Also as noted above, the cDNA deposit is referred to herein as “the deposited clone” or as “the cDNA of the deposited clone.”

The deposited clone was deposited with the American Type Culture Collection, 10801 University Boulevard, Manassas, Va. 20110-2209, USA (present address), on Mar. 6, 1996 and assigned ATCC Deposit No. 97463.

The deposited material is a pBluescript SK (−) plasmid (Stratagene, La Jolla, Calif.) that contains the full length Cystatin F cDNA, referred to as “PF265” upon deposit.

The deposit has been made under the terms of the Budapest Treaty on the international recognition of the deposit of microorganisms for purposes of patent procedure. The strain will be irrevocably and without restriction or condition released to the public upon the issuance of a patent. The deposit is provided merely as convenience to those of skill in the art and is not an admission that a deposit is required for enablement, such as that required under 35 U.S.C. §112.

The sequence of the polynucleotides contained in the deposited material, as well as the amino acid sequence of the polypeptide encoded thereby, are controlling in the event of any conflict with any description of sequences herein.

A license may be required to make, use or sell the deposited materials, and no such license is hereby granted.

Polypeptides

The present invention further relates to a human Cystatin F polypeptide that has the deduced amino acid sequence of FIG. 1 (SEQ ID NO:2).

The invention also relates to fragments, analogs, and derivatives of these polypeptides. The terms “fragment,” “derivative” and “analog” when referring to the polypeptide of FIG. 1 (SEQ ID NO:2) means a polypeptide that retains essentially the same biological function or activity as such polypeptide. Thus, an analog includes a proprotein that can be activated by cleavage of the proprotein portion to produce an active mature polypeptide.

The polypeptide of the present invention may be a recombinant polypeptide, a natural polypeptide, or a synthetic polypeptide. In certain preferred embodiments it is a recombinant polypeptide.

The fragment, derivative or analog of the polypeptide of FIG. 1 (SEQ ID NO:2) may be (i) one in which one or more of the amino acid residues are substituted with a conserved or non-conserved amino acid residue (preferably a conserved amino acid residue) and such substituted amino acid residue may or may not be one encoded by the genetic code, or (ii) one in which one or more of the amino acid residues includes a substituent group, or (iii) one in which the mature polypeptide is fused with another compound, such as a compound to increase the half-life of the polypeptide (for example, polyethylene glycol), or (iv) one in which the additional amino acids are fused to the mature polypeptide, such as a leader or secretory sequence or a sequence which is employed for purification of the mature polypeptide or a proprotein sequence. Such fragments, derivatives, and analogs are deemed to be within the scope of those skilled in the art from the teachings herein.

Among the particularly preferred embodiments of the invention in this regard are polypeptides having the amino acid sequence of Cystatin F set out in FIG. 1 (SEQ ID NO:2), variants, analogs, derivatives and fragments thereof, and variants, analogs and derivatives of the fragments. Alternatively, particularly preferred embodiments of the invention in this regard are polypeptides having the amino acid sequence of the Cystatin F of the cDNA in the deposited clone, variants, analogs, derivatives and fragments thereof, and variants, analogs and derivatives of the fragments.

Among preferred variants are those that vary from a reference by conservative amino acid substitutions. Such substitutions are those that substitute a given amino acid in a polypeptide by another amino acid of like characteristics. Typically seen as conservative substitutions are the replacements, one for another, among the aliphatic amino acids Ala, Val, Leu and Ile; interchange of the hydroxyl residues Ser and Thr, exchange of the acidic residues Asp and Glu, substitution between the amide residues Asn and Gln, exchange of the basic residues Lys and Arg and replacements among the aromatic residues Phe, Tyr.

Further particularly preferred in this regard are variants, analogs, derivatives and fragments, and variants, analogs and derivatives of the fragments, having the amino acid sequence of the Cystatin F polypeptide of FIG. 1 (SEQ ID NO:2) in which several, a few, 5 to 10, 1 to 5, 1 to 3, 2, 1 or no amino acid residues are substituted, deleted or added, in any combination. Especially preferred among these are silent substitutions, additions and deletions, which do not alter the properties and activities of the Cystatin F. Also especially preferred in this regard are conservative substitutions. Most highly preferred are polypeptides having the amino acid sequence of FIG. 1 (SEQ ID NO:2) without substitutions.

The polypeptides and polynucleotides of the present invention are preferably provided in an isolated form, and preferably are purified to homogeneity.

The polypeptides of the present invention also include the polypeptide of SEQ ID NO:2 (in particular the mature polypeptide) as well as polypeptides which have at least 70% similarity (preferably at least 70% identity) to the polypeptide of SEQ ID NO:2 and more preferably at least 90% similarity (more preferably at least 90% identity) to the polypeptide of SEQ ID NO:2 and still more preferably at least 95% similarity (still more preferably at least 95% identity) to the polypeptide of SEQ ID NO:2 and also include portions of such polypeptides with such portion of the polypeptide generally containing at least 30 amino acids and more preferably at least 50 amino acids.

As known in the art “similarity” between two polypeptides is determined by comparing the amino acid sequence and its conserved amino acid substitutes of one polypeptide to the sequence of a second polypeptide.

Fragments or portions of the polypeptides of the present invention may be employed for producing the corresponding full-length polypeptide by peptide synthesis; therefore, the fragments may be employed as intermediates for producing the full-length polypeptides. Fragments or portions of the polynucleotides of the present invention may be used to synthesize full-length polynucleotides of the present invention.

Fragments

Also among preferred embodiments of this aspect of the present invention are polypeptides comprising fragments of Cystatin F, most particularly fragments of the Cystatin F having the amino acid set out in FIG. 1 (SEQ ID NO:2), and fragments of variants and derivatives of the Cystatin F of FIG. 1 (SEQ ID NO:2).

In this regard a fragment is a polypeptide having an amino acid sequence that entirely is the same as part but not all of the amino acid sequence of the aforementioned Cystatin F polypeptides and variants or derivatives thereof.

Such fragments may be “free-standing,” i.e., not part of or fused to other amino acids or polypeptides, or they may be comprised within a larger polypeptide of which they form a part or region. When comprised within a larger polypeptide, the presently discussed fragments most preferably form a single continuous region. However, several fragments may be comprised within a single larger polypeptide. For instance, certain preferred embodiments relate to a fragment of a Cystatin F polypeptide of the present comprised within a precursor polypeptide designed for expression in a host and having heterologous pre and pro-polypeptide regions fused to the amino terminus of the Cystatin F fragment and an additional region fused to the carboxyl terminus of the fragment. Therefore, fragments in one aspect of the meaning intended herein, refer to the portion or portions of a fusion polypeptide or fusion protein derived from Cystatin F.

As representative examples of polypeptide fragments of the invention, there may be mentioned those which have from about 25 to about 145 amino acids. In this context about includes the particularly recited range and ranges larger or smaller by several, a few, 5, 4, 3, 2, or 1 amino acid at either extreme or at both extremes. For instance, about 145 amino acids in this context means a polypeptide fragment of 25 plus or minus several, a few, 5, 4, 3, 2 or 1 amino acids to 145 plus or minus several a few, 5, 4, 3, 2 or 1 amino acid residues, i.e., ranges as broad as 25 minus several amino acids to 145 plus several amino acids to as narrow as 25 plus several amino acids to 145 minus several amino acids.

Highly preferred in this regard are the recited ranges plus or minus as many as 5 amino acids at either or at both extremes. Particularly highly preferred are the recited ranges plus or minus as many as 3 amino acids at either or at both the recited extremes. Especially particularly highly preferred are ranges plus or minus 1 amino acid at either or at both extremes or the recited ranges with no additions or deletions. Most highly preferred of all in this regard are fragments from about 25 to about 145 amino acids.

Among especially preferred fragments of the invention are truncation mutants of Cystatin F. Truncation mutants include Cystatin F polypeptides having the amino acid sequence of FIG. 1 (SEQ ID NO:2), or of variants or derivatives thereof, except for deletion of a continuous series of residues (that is, a continuous region, part or portion) that includes the amino terminus, or a continuous series of residues that includes the carboxyl terminus or, as in double truncation mutants, deletion of two continuous series of residues, one including the amino terminus and one including the carboxyl terminus. Fragments having the size ranges set out about also are preferred embodiments of truncation fragments, which are especially preferred among fragments generally.

Also preferred in this aspect of the invention are fragments characterized by structural or functional attributes of Cystatin F. Preferred embodiments of the invention in this regard include fragments that comprise alpha-helix and alpha-helix forming regions (“alpha-regions”), beta-sheet and beta-sheet-forming regions (“beta-regions”), turn and turn-forming regions (“turn-regions”), coil and coil-forming regions (“coil-regions”), hydrophilic regions, hydrophobic regions, alpha amphipathic regions, beta amphipathic regions, flexible regions, surface-forming regions and high antigenic index regions of Cystatin F.

Certain preferred regions in these regards are set out in FIG. 3, and include, but are not limited to, regions of the aforementioned types identified by analysis of the amino acid sequence set out in FIG. 1 (SEQ ID NO:2). As set out in FIG. 3, such preferred regions include Garnier-Robson alpha-regions, beta-regions, turn-regions and coil-regions, Chou-Fasman alpha-regions, beta-regions and turn-regions, Kyte-Doolittle hydrophilic regions and hydrophilic regions, Eisenberg alpha and beta amphipathic regions, Karplus-Schulz flexible regions, Emini surface-forming regions and Jameson-Wolf high antigenic index regions.

Among highly preferred fragments in this regard are those that comprise regions of Cystatin F that combine several structural features, such as several of the features set out above. In this regard, the regions defined by the residues about 25-145 of FIG. 1 (SEQ ID NO:2), which all are characterized by amino acid compositions highly characteristic of turn-regions, hydrophilic regions, flexible-regions, surface-forming regions, and high antigenic index-regions, are especially highly preferred regions. Such regions may be comprised within a larger polypeptide or may be by themselves a preferred fragment of the present invention, as discussed above. It will be appreciated that the term “about” as used in this paragraph has the meaning set out above regarding fragments in general.

Further preferred regions are those that mediate activities of Cystatin F. Most highly preferred in this regard are fragments that have a chemical, biological or other activity of Cystatin F, including those with a similar activity or an improved activity, or with a decreased undesirable activity. Highly preferred in this regard are fragments that contain regions that are homologs in sequence, or in position, or in both sequence and to active regions of related polypeptides, such as the related polypeptides set out in FIG. 2 (SEQ ID NO:3), which includes human cystatin C. Among particularly preferred fragments in these regards are truncation mutants, as discussed above.

It will be appreciated that the invention also relates to, among others, polynucleotides encoding the aforementioned fragments, polynucleotides that hybridize to polynucleotides encoding the fragments, particularly those that hybridize under stringent conditions, and polynucleotides, such as PCR primers, for amplifying polynucleotides that encode the fragments. In these regards, preferred polynucleotides are those that correspondent to the preferred fragments, as discussed above.

Vectors, Host Cells, Expression

The present invention also relates to vectors that include polynucleotides of the present invention, host cells genetically engineered with vectors of the invention and the production of polypeptides of the invention by recombinant techniques.

Host cells can be genetically engineered to incorporate polynucleotides and express polypeptides of the present invention. For instance, polynucleotides may be introduced into host cells using well-known techniques of infection, transduction, transfection, transvection, and transformation. The polynucleotides may be introduced alone or with other polynucleotides. Such other polynucleotides may be introduced independently, co-introduced or introduced joined to the polynucleotides of the invention.

Thus, for instance, polynucleotides of the invention may be transfected into host cells with another, separate, polynucleotide encoding a selectable marker, using standard techniques for co-transfection and selection in, for instance, mammalian cells. In this case the polynucleotides generally will be stably incorporated into the host cell genome.

Alternatively, the polynucleotides may be joined to a vector containing a selectable marker for propagation in a host. The vector construct may be introduced into host cells by the aforementioned techniques. Generally, a plasmid vector is introduced as DNA in a precipitate, such as a calcium phosphate precipitate, or in a complex with a charged lipid. Electroporation also may be used to introduce polynucleotides into a host. If the vector is a virus, it may be packaged in vitro or introduced into a packaging cell and the packaged virus may be transduced into cells. A wide variety of techniques suitable for making polynucleotides and for introducing polynucleotides into cells in accordance with this aspect of the invention are well known and routine to those of skill in the art. Such techniques are reviewed at length in Sambrook et al. cited above, which is illustrative of the many laboratory manuals that detail these techniques.

In accordance with this aspect of the invention the vector may be, for example, a plasmid vector, a single or double-stranded phage vector, a single or double-stranded RNA or DNA viral vector. Such vectors may be introduced into cells as polynucleotides, preferably DNA, by well-known techniques for introducing DNA and RNA into cells. The vectors, in the case of phage and viral vectors also may be and preferably are introduced into cells as packaged or encapsidated virus by well-known techniques for infection and transduction. Viral vectors may be replication competent or replication defective. In the latter case viral propagation generally will occur only in complementing host cells.

Preferred among vectors, in certain respects, are those for expression of polynucleotides and polypeptides of the present invention. Generally, such vectors comprise cis-acting control regions effective for expression in a host operatively linked to the polynucleotide to be expressed. Appropriate trans-acting factors are supplied by the host, supplied by a complementing vector, or supplied by the vector itself upon introduction into the host.

In certain preferred embodiments in this regard, the vectors provide for specific expression. Such specific expression may be inducible expression or expression only in certain types of cells or both inducible and cell-specific. Particularly preferred among inducible vectors are vectors that can be induced for expression by environmental factors that are easy to manipulate, such as temperature and nutrient additives. A variety of vectors suitable to this aspect of the invention, including constitutive and inducible expression vectors for use in prokaryotic and eukaryotic hosts, are well known and employed routinely by those of skill in the art.

The engineered host cells can be cultured in conventional nutrient media, which may be modified as appropriate for, inter alia, activating promoters, selecting transformants, or amplifying genes. Culture conditions, such as temperature, pH and the like, previously used with the host cell selected for expression generally will be suitable for expression of polypeptides of the present invention as will be apparent to those of skill in the art.

A great variety of expression vectors can be used to express a polypeptide of the invention. Such vectors include chromosomal, episomal and virus-derived vectors e.g., vectors derived from bacterial plasmids, from bacteriophage, from yeast episomes, from yeast chromosomal elements, from viruses such as baculoviruses, papova viruses, such as SV40, vaccinia viruses, adenoviruses, fowl pox viruses, pseudorabies viruses and retroviruses, and vectors derived from combinations thereof, such as those derived from plasmid and bacteriophage genetic elements, such as cosmids and phagemids, all may be used for expression in accordance with this aspect of the present invention. Generally, any vector suitable to maintain, propagate, or express polynucleotides to express a polypeptide in a host may be used for expression in this regard.

The appropriate DNA sequence may be inserted into the vector by any of a variety of well-known and routine techniques. In general, a DNA sequence for expression is joined to an expression vector by cleaving the DNA sequence and the expression vector with one or more restriction endonucleases and then joining the restriction fragments together using T4 DNA ligase. Procedures for restriction and ligation that can be used to this end are well known and routine to those of skill. Suitable procedures in this regard, and for constructing expression vectors using alternative techniques, which also are well known and routine to those skill, are set forth in great detail in Sambrook et al. cited elsewhere herein.

The DNA sequence in the expression vector is operatively linked to appropriate expression control sequence(s), including, for instance, a promoter to direct mRNA transcription. Representatives of such promoters include the phage lambda PL promoter, the E. coli lac, trp and tac promoters, the SV40 early and late promoters and promoters of retroviral LTRs, to name just a few of the well-known promoters. It will be understood that numerous promoters not mentioned are suitable for use in this aspect of the invention are well known and readily may be employed by those of skill in the manner illustrated by the discussion and the examples herein.

In general, expression constructs will contain sites for transcription initiation and termination, and, in the transcribed region, a ribosome-binding site for translation. The coding portion of the mature transcripts expressed by the constructs will include a translation initiating AUG at the beginning and a termination codon appropriately positioned at the end of the polypeptide to be translated.

In addition, the constructs may contain control regions that regulate as well as engender expression. Generally, in accordance with many commonly practiced procedures, such regions will operate by controlling transcription, such as repressor binding sites and enhancers, among others.

Vectors for propagation and expression generally will include selectable markers. Such markers also may be suitable for amplification or the vectors may contain additional markers for this purpose. In this regard, the expression vectors preferably contain one or more selectable marker genes to provide a phenotypic trait for selection of transformed host cells. Preferred markers include dihydrofolate reductase or neomycin resistance for eukaryotic cell culture, and tetracycline, theomycin, kanamycin or ampicillin resistance genes for culturing E. coli, and other bacteria.

The vector containing the appropriate DNA sequence as described elsewhere herein, as well as an appropriate promoter, and other appropriate control sequences, may be introduced into an appropriate host using a variety of well-known techniques suitable to expression therein of a desired polypeptide. Representative examples of appropriate hosts include bacterial cells, such as E. coli, Streptomyces and Salmonella typhimurium cells; fungal cells, such as yeast cells; insect cells such as Drosophila S2 and Spodoptera Sf9 cells; animal cells such as CHO, COS and Bowes melanoma cells; and plant cells. Hosts for of a great variety of expression constructs are well known, and those of skill will be enabled by the present disclosure readily to select a host for expressing polypeptides in accordance with this aspect of the present invention.

Various mammalian cell culture systems can be employed for expression, as well. Examples of mammalian expression systems include the COS-7 lines of monkey kidney fibroblast, described in Gluzman et al., Cell 23: 175 (1981). Other cell lines capable of expressing a compatible vector include for example, the C127, 3T3, CHO, HeLa, human kidney 293 and BHK cell lines.

More particularly, the present invention also includes recombinant constructs, such as expression constructs, comprising one or more of the sequences described above. The constructs comprise a vector, such as a plasmid or viral vector, into which such a sequence of the invention has been inserted. The sequence may be inserted in a forward or reverse orientation. In certain preferred embodiments in this regard, the construct further comprises regulatory sequences, including, for example, a promoter, operably linked to the sequence. Large numbers of suitable vectors and promoters are known to those of skill in the art, and there are many commercially available vectors suitable for use in the present invention.

The following vectors, which are commercially available, are provided by way of example. Among vectors preferred for use in bacteria are pHE4-5 (ATCC Accession No. 209311; and variations thereof), pQE70, pQE60, and pQE-9, available from Qiagen; pBS vectors, Phagescript vectors, Bluescript vectors, pNH8A, pNH16a, pNH18A, pNH46A, available from Stratagene; and ptrc99a, pKK223-3, pKK233-3, pDR540, pRIT5 available from Pharmacia. Among preferred eukaryotic vectors are pWLNEO, pSV2CAT, pOG44, pXT1 and pSG available from Stratagene; and pSVK3, pBPV, pMSG and pSVL available from Pharmacia. These vectors are listed solely by way of illustration of the many commercially available and well-known vectors that are available to those of skill in the art for use in accordance with this aspect of the present invention. It will be appreciated that any other plasmid or vector suitable for, for example, introduction, maintenance, propagation or expression of a polynucleotide or polypeptide of the invention in a host may be used in this aspect of the invention.

Promoter regions can be selected from any desired gene using vectors that contain a reporter transcription unit lacking a promoter region, such as a chloramphenicol acetyl transferase (“cat”) transcription unit, downstream of restriction site or sites for introducing a candidate promoter fragment; i.e., a fragment that may contain a promoter. As is well known, introduction into the vector of a promoter-containing fragment at the restriction site upstream of the cat gene engenders production of CAT activity, which can be detected by standard CAT assays. Vectors suitable to this end are well known and readily available. Two such vectors are pKK232-8 and pCM7. Thus, promoters for expression of polynucleotides of the present invention include not only well-known and readily available promoters, but also promoters that readily may be obtained by the foregoing technique, using a reporter gene.

Among known bacterial promoters suitable for expression of polynucleotides and polypeptides in accordance with the present invention are the E. coli lacI and lacZ promoters, the T3 and T7 promoters, the T5 tac promoter, the lambda PR, PL promoters and the trp promoter. Among known eukaryotic promoters suitable in this regard are the CMV immediate early promoter, the HSV thymidine kinase promoter, the early and late SV40 promoters, the promoters of retroviral LTRs, such as those of the Rous sarcoma virus (“RSV”), and metallothionein promoters, such as the mouse metallothionein-I promoter.

Selection of appropriate vectors and promoters for expression in a host cell is a well-known procedure and the requisite techniques for expression vector construction, introduction of the vector into the host and expression in the host are routine skills in the art.

Generally, recombinant expression vectors will include origins of replication, a promoter derived from a highly expressed gene to direct transcription of a downstream structural sequence, and a selectable marker to permit isolation of vector containing cells after exposure to the vector.

The present invention also relates to host cells containing the above-described constructs discussed above. The host cell can be a higher eukaryotic cell, such as a mammalian cell, or a lower eukaryotic cell, such as a yeast cell, or the host cell can be a prokaryotic cell, such as a bacterial cell.

Constructs in host cells can be used in a conventional manner to produce the gene product encoded by the recombinant sequence. Alternatively, conventional peptide synthesizers can synthetically produce the polypeptides of the invention.

Mature proteins can be expressed in mammalian cells, yeast, bacteria, or other cells under the control of appropriate promoters. Cell-free translation systems can also be employed to produce such proteins using RNAs derived from the DNA constructs of the present invention. Appropriate cloning and expression vectors for use with prokaryotic and eukaryotic hosts are described by Sambrook et al., MOLECULAR CLONING: A LABORATORY MANUAL, 2nd Ed., Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. (1989).

Inserting an enhancer sequence into the vector may increase transcription of the DNA encoding the polypeptides of the present invention by higher eukaryotes. Enhancers are cis-acting elements of DNA, usually about from 10 to 300 bp that act to increase transcriptional activity of a promoter in a given host cell-type. Examples of enhancers include the SV40 enhancer, which is located on the late side of the replication origin at bp 100 to 270, the cytomegalovirus early promoter enhancer, the polyoma enhancer on the late side of the replication origin, and adenovirus enhancers.

Polynucleotides of the invention, encoding the heterologous structural sequence of a polypeptide of the invention generally will be inserted into the vector using standard techniques so that it is operably linked to the promoter for expression. The polynucleotide will be positioned so that the transcription start site is located appropriately 5′ to a ribosome binding site. The ribosome-binding site will be 5′ to the AUG that initiates translation of the polypeptide to be expressed. Generally, there will be no other open reading frames that begin with an initiation codon, usually AUG, and lie between the ribosome binding site and the initiating AUG. Also, generally, there will be a translation stop codon at the end of the polypeptide and there will be a polyadenylation signal and a transcription termination signal appropriately disposed at the 3′ end of the transcribed region.

For secretion of the translated protein into the lumen of the endoplasmic reticulum, into the periplasmic space or into the extracellular environment, appropriate secretion signals may be incorporated into the expressed polypeptide. The signals may be endogenous to the polypeptide or they may be heterologous signals.

The polypeptide may be expressed in a modified form, such as a fusion protein, and may include not only secretion signals but also additional heterologous functional regions. Thus, for instance, a region of additional amino acids, particularly charged amino acids, may be added to the N-terminus of the polypeptide to improve stability and persistence in the host cell, during purification or during subsequent handling and storage. Also, region also may be added to the polypeptide to facilitate purification. Such regions may be removed prior to final preparation of the polypeptide. The addition of peptide moieties to polypeptides to engender secretion or excretion, to improve stability and to facilitate purification, among others, is familiar and routine techniques in the art.

Following transformation of a suitable host strain and growth of the host strain to an appropriate cell density, where the selected promoter is inducible it is induced by appropriate means (e.g., temperature shift or exposure to chemical inducer) and cells are cultured for an additional period.

Cells typically then are harvested by centrifugation, disrupted by physical or chemical means, and the resulting crude extract retained for further purification.

Microbial cells employed in expression of proteins can be disrupted by any convenient method, including freeze-thaw cycling, sonication, mechanical disruption, or use of cell lysing agents, such methods are well know to those skilled in the art.

The Cystatin F polypeptide can be recovered and purified from recombinant cell cultures by well-known methods including ammonium sulfate or ethanol precipitation, acid extraction, anion or cation exchange chromatography, phosphocellulose chromatography, hydrophobic interaction chromatography, affinity chromatography, hydroxylapatite chromatography and lectin chromatography. Most preferably, high performance liquid chromatography (“HPLC”) is employed for purification. Well-known techniques for refolding protein may be employed to regenerate active conformation when the polypeptide is denatured during isolation and or purification.

Polypeptides of the present invention include naturally purified products, products of chemical synthetic procedures, and products produced by recombinant techniques from a prokaryotic or eukaryotic host, including, for example, bacterial, yeast, higher plant, insect and mammalian cells. Depending upon the host employed in a recombinant production procedure, the polypeptides of the present invention may be glycosylated or may be non-glycosylated. In addition, polypeptides of the invention may also include an initial modified methionine residue, in some cases as a result of host-mediated processes.

Cystatin F polynucleotides and polypeptides may be used in accordance with the present invention for a variety of applications, particularly those that make use of the chemical and biological properties of Cystatin F. Among these are applications in inhibition of cysteine proteases. Additional applications relate to diagnosis and to treatment of disorders of cells, tissues, and organisms. These aspects of the invention are illustrated further by the following discussion.

Polynucleotide Assays

This invention is also related to the use of the Cystatin F polynucleotides to detect complementary polynucleotides such as, for example, as a diagnostic reagent. Detection of a mutated form of Cystatin F associated with a dysfunction will provide a diagnostic tool that can add or define a diagnosis of a disease or susceptibility to a disease which results from under-expression over-expression or altered expression of Cystatin F, such as, for example, neoplasia and HCCAA.

Individuals carrying mutations in the human Cystatin F gene may be detected at the DNA level by a variety of techniques. Nucleic acids for diagnosis may be obtained from a patient's cells, such as from blood, urine, saliva, tissue biopsy and autopsy material. The genomic DNA may be used directly for detection or may be amplified enzymatically by using PCR prior to analysis. PCR (Saiki et al., Nature, 324: 163-166 (1986)). RNA or cDNA may also be used in the same ways. As an example, PCR primers complementary to the nucleic acid encoding Cystatin F can be used to identify and analyze Cystatin F expression and mutations. For example, deletions and insertions can be detected by a change in size of the amplified product in comparison to the normal genotype. Point mutations can be identified by hybridizing amplified DNA to radio labeled Cystatin F RNA or alternatively, radio labeled Cystatin F antisense DNA sequences. Perfectly matched sequences can be distinguished from mismatched duplexes by RNase A digestion or by differences in melting temperatures.

Sequence differences between a reference gene and genes having mutations also may be revealed by direct DNA sequencing. In addition, cloned DNA segments may be employed as probes to detect specific DNA segments. The sensitivity of such methods can be greatly enhanced by appropriate use of PCR or another amplification method. For example, a sequencing primer is used with double-stranded PCR product or a single-stranded template molecule generated by a modified PCR. The sequence determination is performed by conventional procedures with radio labeled nucleotide or by automatic sequencing procedures with fluorescent-tags.

Genetic testing based on DNA sequence differences may be achieved by detection of alteration in electrophoretic mobility of DNA fragments in gels, with or without denaturing agents. Small sequence deletions and insertions can be visualized by high-resolution gel electrophoresis. DNA fragments of different sequences may be distinguished on denaturing formamide gradient gels in which the motilities of different DNA fragments are retarded in the gel at different positions according to their specific melting or partial melting temperatures (see, e.g., Myers et al., Science, 230: 1242 (1985)).

Sequence changes at specific locations also may be revealed by nuclease protection assays, such as RNase and S1 protection or the chemical cleavage method (e.g., Cotton et al., Proc. Natl. Acad. Sci., USA, 85: 4397-4401 (1985)).

Thus, the detection of a specific DNA sequence may be achieved by methods such as hybridization, RNase protection, chemical cleavage, direct DNA sequencing or the use of restriction enzymes, (e.g., restriction fragment length polymorphisms (“RFLP”) and Southern blotting of genomic DNA.

In addition to more conventional gel-electrophoresis and DNA sequencing, mutations also can be detected by in situ analysis.

Chromosome Assays

The sequences of the present invention are also valuable for chromosome identification. The sequence is specifically targeted to and can hybridize with a particular location on an individual human chromosome. Moreover, there is a current need for identifying particular sites on the chromosome. Few chromosome marking reagents based on actual sequence data (repeat polymorphisms) are presently available for marking chromosomal location. The mapping of DNAs to chromosomes according to the present invention is an important first step in correlating those sequences with genes associated with disease.

In certain preferred embodiments in this regard, the cDNA herein disclosed is used to clone genomic DNA of a Cystatin F gene. This can be accomplished using a variety of well-known techniques and libraries, which generally are available commercially. The genomic DNA is used for in situ chromosome mapping using well-known techniques for this purpose. Typically, in accordance with routine procedures for chromosome mapping, some trial and error may be necessary to identify a genomic probe that gives a good in situ hybridization signal.

In some cases, in addition, sequences can be mapped to chromosomes by preparing PCR primers (preferably 15-25 bp) from the cDNA. Computer analysis of the 3′ untranslated region of the gene is used to rapidly select primers that do not span more than one exon in the genomic DNA, thus complicating the amplification process. These primers are then used for PCR screening of somatic cell hybrids containing individual human chromosomes. Only those hybrids containing the human gene corresponding to the primer will yield an amplified fragment.

PCR mapping of somatic cell hybrids is a rapid procedure for assigning a particular DNA to a particular chromosome. Using the present invention with the same oligonucleotide primers, sublocalization can be achieved with panels of fragments from specific chromosomes or pools of large genomic clones in an analogous manner. Other mapping strategies that can similarly be used to map to its chromosome include in situ hybridization, prescreening with labeled flow-sorted chromosomes and preselection by hybridization to construct chromosome specific-cDNA libraries.

Fluorescence in situ hybridization (“FISH”) of a cDNA clone to a metaphase chromosomal spread can be used to provide a precise chromosomal location in one step. This technique can be used with cDNA as short as 50 or 60 bases. For a review of this technique, see Verma et al., HUMAN CHROMOSOMES: A MANUAL OF BASIC TECHNIQUES, Pergamon Press, New York (1988).

Once a sequence has been mapped to a precise chromosomal location, the physical position of the sequence on the chromosome can be correlated with genetic map data. Such data are found, for example, in V. McKusick, MENDELIAN INHERITANCE IN MAN, available on line through Johns Hopkins University, Welch Medical Library. The relationship between genes and diseases that have been mapped to the same chromosomal region are then identified through linkage analysis (coinheritance of physically adjacent genes).

Next, it is necessary to determine the differences in the cDNA or genomic sequence between affected and unaffected individuals. If a mutation is observed in some or all of the affected individuals but not in any normal individuals, then the mutation is likely to be the causative agent of the disease.

With current resolution of physical mapping and genetic mapping techniques, a cDNA precisely localized to a chromosomal region associated with the disease could be one of between 50 and 500 potential causative genes. (This assumes 1 megabase mapping resolution and one gene per 20 kb).

Polypeptide Assays

The present invention also relates to a diagnostic assays such as quantitative and diagnostic assays for detecting levels of Cystatin F protein in cells and tissues, including determination of normal and abnormal levels. Thus, for instance, a diagnostic assay in accordance with the invention for detecting over-expression of Cystatin F protein compared to normal control tissue samples may be used to detect the presence of neoplasia, for example, tumors. Assay techniques that can be used to determine levels of a protein, such as a Cystatin F protein of the present invention, in a sample derived from a host are well-known to those of skill in the art. Such assay methods include radioimmunoassays, competitive-binding assays, Western Blot analysis, and ELISA assays. Among these ELISAs frequently are preferred. An ELISA assay initially comprises preparing an antibody specific to Cystatin F, preferably a monoclonal antibody. In addition a reporter antibody generally is prepared which binds to the monoclonal antibody. The reporter antibody is attached a detectable reagent such as radioactive, fluorescent or enzymatic reagent, in this example horseradish peroxidase enzyme.

To carry out an ELISA a sample is removed from a host and incubated on a solid support, e.g. a polystyrene dish, which binds the proteins in the sample. Any free protein binding sites on the dish are then covered by incubating with a non-specific protein such as bovine serum albumin. Next, the monoclonal antibody is incubated in the dish during which time the monoclonal antibodies attach to any Cystatin F proteins attached to the polystyrene dish. Unbound monoclonal antibody is washed out with buffer. The reporter antibody linked to horseradish peroxidase is placed in the dish resulting in binding of the reporter antibody to any monoclonal antibody bound to Cystatin F. Unattached reporter antibody is then washed out. Reagents for peroxidase activity, including a colorimetric substrate are then added to the dish. Immobilized peroxidase, linked to Cystatin F through the primary and secondary antibodies, produces a colored reaction product. The amount of color developed in a given time period indicates the amount of Cystatin F protein present in the sample. Quantitative results typically are obtained by reference to a standard curve.

A competition assay may be employed wherein antibodies specific to Cystatin F attached to a solid support and labeled Cystatin F and a sample derived from the host are passed over the solid support and the amount of label detected attached to the solid support can be correlated to a quantity of Cystatin F in the sample.

Antibodies

The polypeptides, their fragments or other derivatives, or analogs thereof, or cells expressing them can be used as an immunogen to produce antibodies thereto. These antibodies can be, for example, polyclonal or monoclonal antibodies. The present invention also includes chimeric, single chain, and humanized antibodies, as well as Fab fragments, or the product of an Fab expression library. Various procedures known in the art may be used for the production of such antibodies and fragments.

Antibodies generated against the polypeptides corresponding to a sequence of the present invention can be obtained by direct injection of the polypeptides into an animal or by administering the polypeptides to an animal, preferably a nonhuman. The antibody so obtained will then bind the polypeptides itself. In this manner, even a sequence encoding only a fragment of the polypeptides can be used to generate antibodies binding the whole native polypeptides. Such antibodies can then be used to isolate the polypeptide from tissue expressing that polypeptide.

For preparation of monoclonal antibodies, any technique that provides antibodies produced by continuous cell line cultures can be used. Examples include the hybridoma technique (Kohler, G. and Milstein, C., Nature 256: 495-497 (1975), the trioma technique, the human B-cell hybridoma technique (Kozbor et al., Immunology Today 4: 72 (1983) and the EBV-hybridoma technique to produce human monoclonal antibodies (Cole et al., pg. 77-96 in MONOCLONAL ANTIBODIES AND CANCER THERAPY, Alan R. Liss, Inc. (1985).

Techniques described for the production of single chain antibodies (U.S. Pat. No. 4,946,778) can be adapted to produce single chain antibodies to immunogenic polypeptide products of this invention. Also, transgenic mice, or other organisms such as other mammals, may be used to express humanized antibodies to immunogenic polypeptide products of this invention.

The above-described antibodies may be employed to isolate or to identify clones expressing the polypeptide or purify the polypeptide of the present invention by attachment of the antibody to a solid support for isolation and/or purification by affinity chromatography.

Thus, among others, human Cystatin F of the present invention may be employed to block growth of group A streptococci and replication of the herpes simplex virus and human coronaviruses.

Cystatin F may also be employed to prevent local and systemic inflammation and to modify inflammatory and necrobiotic processes in heart tissue.

Cystatin F may also be employed to prevent HCCAA caused by mutated Cystatin F. Cystatin F may also be employed to cause turnover and remodeling of the stroma of the eye and to protect the retina against the harmful effects of cysteine proteases.

Cystatin F may also be employed to treat immunological disorders since the Cystatin F gene is highly specific for T-cells and regulates T-cell function.

Cystatin F Binding Molecules and Assays

This invention also provides a method for identification of molecules, such as receptor molecules, that bind Cystatin F. Genes encoding proteins that bind Cystatin F, such as receptor proteins, can be identified by numerous methods known to those of skill in the art, for example, ligand panning, and FACS sorting. Such methods are described in many laboratory manuals such as, for instance, Coligan et al., Current Protocols in Immunology 1(2): Chapter 5 (1991).

For instance, expression cloning may be employed for this purpose. To this end polyadenylated RNA is prepared from a cell responsive to Cystatin F, a cDNA library is created from this RNA, the library is divided into pools and the pools are transfected individually into cells that are not responsive to Cystatin F. The transfected cells then are exposed to labeled Cystatin F. (Cystatin F can be labeled by a variety of well-known techniques including standard methods of radio-iodination or inclusion of a recognition site for a site-specific protein kinase.) Following exposure, the cells are fixed and binding of Cystatin F is determined. These procedures conveniently are carried out on glass slides.

Pools are identified of cDNA that produced Cystatin F-binding cells. Sub-pools are prepared from these positives, transfected into host cells and screened as described above. Using an iterative sub-pooling and re-screening process, plasmids containing one or more single clones that encode the putative binding molecule, such as a receptor molecule, can be isolated and the clones are sequenced.

Alternatively a labeled ligand can be photoaffinity linked to a cell extract, such as a membrane or a membrane extract, prepared from cells that express a molecule that it binds, such as a receptor molecule. Cross-linked material is resolved by polyacrylamide gel electrophoresis (“PAGE”) and exposed to X-ray film. The labeled complex containing the ligand-receptor can be excised, resolved into peptide fragments, and subjected to protein microsequencing. The amino acid sequence obtained from microsequencing can be used to design unique or degenerate oligonucleotide probes to screen cDNA libraries to identify genes encoding the putative receptor molecule.

Polypeptides of the invention also can be used to assess Cystatin F binding capacity of Cystatin F binding molecules, such as receptor molecules, in cells or in cell-free preparations.

Agonists and Antagonists—Assays and Molecules

The invention also provides a method of screening compounds to identify those that enhance or block the action of Cystatin F on cells, such as its interaction with Cystatin F-binding molecules such as receptor molecules. An agonist is a compound which increases the natural biological functions of Cystatin F or which functions in a manner similar to Cystatin F, while antagonists decrease or eliminate such functions.

For example, a cellular compartment, such as a membrane or a preparation thereof, such as a membrane-preparation, may be prepared from a cell that expresses a molecule that binds Cystatin F, such as a molecule of a signaling or regulatory pathway modulated by Cystatin F. The preparation is incubated with labeled Cystatin F in the absence or the presence of a candidate molecule that may be a Cystatin F agonist or antagonist. The ability of the candidate molecule to bind the binding molecule is reflected in decreased binding of the labeled ligand. Molecules which bind gratuitously, i.e., without inducing the effects of Cystatin F on binding the Cystatin F binding molecule, are most likely to be good antagonists. Molecules that bind well and elicit effects that are the same as or closely related to Cystatin F, are good agonists.

Cystatin F-like effects of potential agonists and antagonists may by measured, for instance, by determining activity of a second messenger system following interaction of the candidate molecule with a cell or appropriate cell preparation, and comparing the effect with that of Cystatin F or molecules that elicit the same effects as Cystatin F. Second messenger systems that may be useful in this regard include but are not limited to AMP guanylate cyclase, ion channel, or phosphoinositide hydrolysis second messenger systems.

Another example of an assay for Cystatin F antagonists is a competitive assay that combines Cystatin F and a potential antagonist with membrane-bound Cystatin F receptor molecules or recombinant Cystatin F receptor molecules under appropriate conditions for a competitive inhibition assay. Cystatin F can be labeled, such as by radioactivity, such that the number of Cystatin F molecules bound to a receptor molecule can be determined accurately to assess the effectiveness of the potential antagonist.

Potential antagonists include small organic molecules, peptides, polypeptides and antibodies that bind to a polypeptide of the invention and thereby inhibit or extinguish its activity, for example, a polypeptide such as a closely related protein or antibody that binds the same sites on a binding molecule, such as a receptor molecule, without inducing Cystatin F-induced activities, thereby preventing the action of Cystatin F by excluding Cystatin F from binding.

Other potential antagonists include antisense molecules. Antisense technology can be used to control gene expression through antisense DNA or RNA or through triple-helix formation. Antisense techniques are discussed, for example, in—Okano, J. Neurochem. 56: 560 (1991); OLIGODEOXYNUCLEOTIDES AS ANTISENSE INHIBITORS OF GENE EXPRESSION, CRC Press, Boca Raton, Fla. (1988). Triple helix formation is discussed in, for instance Lee et al., Nucleic Acids Research 6: 3073 (1979); Cooney et al., Science 241: 456 (1988); and Dervan et al., Science 251: 1360 (1991). The methods are based on binding of a polynucleotide to a complementary DNA or RNA. For example, the 5′ coding portion of a polynucleotide that encodes the mature polypeptide of the present invention may be used to design an antisense RNA oligonucleotide of from about 10 to 40 base pairs in length. A DNA oligonucleotide is designed to be complementary to a region of the gene (or promoter) involved in transcription thereby preventing transcription and the production of Cystatin F. The antisense RNA oligonucleotide hybridizes to the mRNA in vivo and blocks translation of the mRNA molecule into Cystatin F polypeptide. The oligonucleotides described above can also be delivered to cells such that the antisense RNA or DNA may be expressed in vivo to inhibit production of Cystatin F.

The antagonists may be employed in a composition with a pharmaceutically acceptable carrier, e.g., as hereinafter described.

The antagonists may be employed for instance to treat and/or prevent cerebral hemorrhages and leukoencephalopathy.

The antagonists may also be employed to treat and/or prevent tumors and other neoplasia and to block HIV infection.

Compositions

The invention also relates to compositions comprising the polynucleotide or the polypeptides discussed above or the agonists or antagonists. Thus, the polypeptides of the present invention may be employed in combination with a non-sterile or sterile carrier or carriers for use with cells, tissues, or organisms, such as a pharmaceutical carrier suitable for administration to a subject. Such compositions comprise, for instance, a media additive or a therapeutically effective amount of a polypeptide of the invention and a pharmaceutically acceptable carrier or excipient. Such carriers may include, but are not limited to, saline, buffered saline, dextrose, water, glycerol, ethanol, and combinations thereof. The formulation should suit the mode of administration.

Kits

The invention further relates to pharmaceutical packs and kits comprising one or more containers filled with one or more of the ingredients of the aforementioned compositions of the invention. Associated with such container(s) can be a notice in the form prescribed by a governmental agency regulating the manufacture, use, or sale of pharmaceuticals or biological products, reflecting approval by the agency of the manufacture, use, or sale of the product for human administration.

Administration

Polypeptides and other compounds of the present invention may be employed alone or in conjunction with other compounds, such as therapeutic compounds.

The pharmaceutical compositions may be administered in any effective, convenient manner including, for instance, administration by topical, oral, anal, vaginal, intravenous, intraperitoneal, intramuscular, subcutaneous, intranasal, or intradermal routes among others.

The pharmaceutical compositions generally are administered in an amount effective for treatment or prophylaxis of a specific indication or indications. In general, the compositions are administered in an amount of at least about 10-mg/kg body weight. In most cases they will be administered in an amount not in excess of about 8-mg/kg body weight per day. Preferably, in most cases, dose is from about 10 mg/kg to about 1 mg/kg body weight, daily. It will be appreciated that optimum dosage will be determined by standard methods for each treatment modality and indication, taking into account the indication, its severity, route of administration, complicating conditions and the like.

Gene Therapy

The Cystatin F polynucleotides, polypeptides, agonists and antagonists that are polypeptides may be employed in accordance with the present invention by expression of such polypeptides in vivo, in treatment modalities often referred to as “gene therapy.”

Thus, for example, cells from a patient may be engineered with a polynucleotide, such as a DNA or RNA, encoding a polypeptide ex vivo, and the engineered cells then can be provided to a patient to be treated with the polypeptide. For example, cells may be engineered ex vivo by the use of a retroviral plasmid vector containing RNA encoding a polypeptide of the present invention. Such methods are well-known in the art and their use in the present invention will be apparent from the teachings herein.

Similarly, cells may be engineered in vivo for expression of a polypeptide in vivo by procedures known in the art. For example, a polynucleotide of the invention may be engineered for expression in a replication defective retroviral vector, as discussed above. The retroviral expression construct then may be isolated and introduced into a packaging cell is transduced with a retroviral plasmid vector containing RNA encoding a polypeptide of the present invention such that the packaging cell now produces infectious viral particles containing the gene of interest. These producer cells may be administered to a patient for engineering cells in vivo and expression of the polypeptide in vivo. These and other methods for administering a polypeptide of the present invention by such method should be apparent to those skilled in the art from the teachings of the present invention.

Retroviruses from which the retroviral plasmid vectors herein above mentioned may be derived include, but are not limited to, Moloney Murine Leukemia Virus, spleen necrosis virus, retroviruses such as Rous Sarcoma Virus, Harvey Sarcoma Virus, avian leukosis virus, gibbon ape leukemia virus, human immunodeficiency virus, adenovirus, Myeloproliferative Sarcoma Virus, and mammary tumor virus. In one embodiment, the retroviral plasmid vector is derived from Moloney Murine Leukemia Virus.

Such vectors well include one or more promoters for expressing the polypeptide. Suitable promoters which may be employed include, but are not limited to, the retroviral LTR; the SV40 promoter; and the human cytomegalovirus (CMV) promoter described in Miller et al., Biotechniques 7: 980-990 (1989), or any other promoter (e.g., cellular promoters such as eukaryotic cellular promoters including, but not limited to, the histone, RNA polymerase III, and β-actin promoters). Other viral promoters that may be employed include, but are not limited to, adenovirus promoters, thymidine kinase (TK) promoters, and B19 parvovirus promoters. The selection of a suitable promoter will be apparent to those skilled in the art from the teachings contained herein.

The nucleic acid sequence encoding the polypeptide of the present invention will be placed under the control of a suitable promoter. Suitable promoters which may be employed include, but are not limited to, adenoviral promoters, such as the adenoviral major late promoter; or heterologous promoters, such as the cytomegalovirus (CMV) promoter; the respiratory syncytial virus (RSV) promoter; inducible promoters, such as the MMT promoter, the metallothionein promoter; heat shock promoters; the albumin promoter; the ApoAI promoter; human globin promoters; viral thymidine kinase promoters, such as the Herpes Simplex thymidine kinase promoter; retroviral LTRs (including the modified retroviral LTRs herein above described); the β-actin promoter; and human growth hormone promoters. The promoter also may be the native promoter that controls the gene encoding the polypeptide.

The retroviral plasmid vector is employed to transduce packaging cell lines to form producer cell lines. Examples of packaging cells which may be transfected include, but are not limited to, the PE501, PA317, Y-2, Y-AM, PA12, T19-14×, VT-19-17-H2, YCRE, YCRIP, GP+E-86, GP+envAm12, and DAN cell lines as described in Miller, A., Human Gene Therapy 1: 5-14 (1990). The vector may be transduced into the packaging cells through any means known in the art. Such means include, but are not limited to, electroporation, the use of liposomes, and CaPO4 precipitation. In one alternative, the retroviral plasmid vector may be encapsulated into a liposome, or coupled to a lipid, and then administered to a host.

The producer cell line will generate infectious retroviral vector particles, which include the nucleic acid sequence(s) encoding the polypeptides. Such retroviral vector particles then may be employed to transduce eukaryotic cells, either in vitro or in vivo. The transduced eukaryotic cells will express the nucleic acid sequence(s) encoding the polypeptide. Eukaryotic cells that may be transduced include, but are not limited to, embryonic stem cells, embryonic carcinoma cells, as well as hematopoietic stem cells, hepatocytes, fibroblasts, myoblasts, keratinocytes, endothelial cells, and bronchial epithelial cells.

EXAMPLES

The present invention is further described by the following examples. The examples are provided solely to illustrate the invention by reference to specific embodiments. These exemplifications, while illustrating certain specific aspects of the invention, do not portray the limitations or circumscribe the scope of the disclosed invention.

Certain terms used herein are explained in the foregoing glossary.

All examples were carried out using standard techniques, which are well known and routine to those of skill in the art, except where otherwise described in detail. Routine molecular biology techniques of the following examples can be carried out as described in standard laboratory manuals, such as Sambrook et al., MOLECULAR CLONING: A LABORATORY MANUAL, 2nd Ed.; Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. (1989), herein referred to as “Sambrook.”

All parts or amounts set out in the following examples are by weight, unless otherwise specified.

Unless otherwise stated size separation of fragments in the examples below was carried out using standard techniques of agarose and polyacrylamide gel electrophoresis (“PAGE”) in Sambrook and numerous other references such as, for instance, by Goeddel et al., Nucleic Acids Res. 8: 4057 (1980).

Unless described otherwise, ligations were accomplished using standard buffers, incubation temperatures, and times, approximately equimolar amounts of the DNA fragments to be ligated and approximately 10 units of T4 DNA ligase (“ligase”) per 0.5 mg of DNA.

Example 1 Expression and Purification of Mature Human Cystatin F Using Bacteria

The DNA sequence encoding human Cystatin F in the deposited polynucleotide is amplified using PCR oligonucleotide primers specific to the amino acid carboxyl terminal sequence of the human Cystatin F protein and to vector sequences 3′ to the gene. Additional nucleotides containing restriction sites to facilitate cloning are added to the 5′ and 3′ sequences respectively.

The 5′ oligonucleotide primer had the sequence 5′ CGC CCA TGG GGG GCC CTT CCC CAG AT 3′ (SEQ ID NO:9) containing the underlined Nco I restriction site, which encodes a start AUG, followed by 18 nucleotides of the human Cystatin F coding sequence set out in FIG. 1 (SEQ ID NO:1) beginning with the first base of the fourth codon of the mature sequence.

The 3′ primer had the sequence 5′ CGC AAG CTT CTG AAG AGG CGG GGG TCA 3′ (SEQ ID NO:10) containing the underlined Hind III restriction site followed by 18 nucleotides complementary to non-coding sequence set out in FIG. 1 (SEQ ID NO:1), including the stop codon.

The restrictions sites are convenient to restriction enzyme sites in the bacterial expression vectors pQE-9 that are used for bacterial expression in these examples. (Qiagen, Inc. Chatsworth, Calif.). pQE-9 encodes ampicillin antibiotic resistance (“Ampr”) and contains a bacterial origin of replication (“ori”), an IPTG inducible promoter, a ribosome binding site (“RBS”), a 6-His tag, and restriction enzyme sites.

The amplified human Cystatin F DNA and the vector pQE-9 both are digested with Nco I and Hind m and the digested DNAs then are ligated together. Insertion of the Cystatin F DNA into the restricted vector placed the Cystatin F coding region downstream of and operably linked to the vector's IPTG-inducible promoter and in-frame with an initiating AUG appropriately positioned for translation of Cystatin F.

The ligation mixture is transformed into competent E. coli cells using standard procedures. Such procedures are described in Sambrook et al., MOLECULAR CLONING: A LABORATORY MANUAL, 2nd Ed.; Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. (1989). E. coli strain M15/rep4, containing multiple copies of the plasmid pREP4, which expresses lac repressor and confers kanamycin resistance (“Kanr”), is used in carrying out the illustrative example described here. This strain, which is only one of many that are suitable for expressing Cystatin F, is available commercially from Qiagen.

Transformants are identified by their ability to grow on LB plates in the presence of ampicillin. Plasmid DNA is isolated from resistant colonies and the identity of the cloned DNA is confirmed by restriction analysis.

Clones containing the desired constructs are grown overnight (“O/N”) in liquid culture in LB media supplemented with both ampicillin (100 μg/ml) and kanamycin (25 μg/ml).

The O/N culture is used to inoculate a large culture, at a dilution of approximately 1:100 to 1:250. The cells are grown to an optical density at 600 nm (“OD600”) of between 0.4 and 0.6. Isopropyl-B-D-thiogalactopyranoside (“IPTG”) is then added to a final concentration of 1 mM to induce transcription from lac repressor sensitive promoters, by inactivating the lacI repressor. Cells subsequently are incubated further for 3 to 4 hours. Cells then are harvested by centrifugation and disrupted, by standard methods. Inclusion bodies are purified from the disrupted cells using routine collection techniques, and protein is solubilized from the inclusion bodies into 8M urea. The 8M urea solution containing the solubilized protein is passed over a PD-10 column in 2× phosphate buffered saline (“PBS”), thereby removing the urea, exchanging the buffer and refolding the protein. The protein is purified by a further step of chromatography to remove endotoxin. Then, it is sterile filtered. The sterile filtered protein preparation is stored in 2×PBS at a concentration of 95 micrograms per mL.

Example 2 Cloning and Expression of Human Cystatin F in a Baculovirus Expression System

The cDNA sequence encoding the full length human Cystatin F protein, in the deposited clone is amplified using PCR oligonucleotide primers corresponding to the 5′ and 3′ sequences of the gene:

The 5′ primer has the sequence 5′ CGC GGA TCC GCC ATC ATG CGA GCG GCT GGA 3′ (SEQ ID NO:11) containing the underlined Bam HI restriction enzyme site followed by 6 bases resembling an efficient Kozak sequence plus 15 bases of the sequence of Cystatin F of FIG. 1 (SEQ ID NO:1). Inserted into an expression vector, as described below, the 5′ end of the amplified fragment encoding human Cystatin F provides an efficient signal peptide. An efficient signal for initiation of translation in eukaryotic cells, as described by Kozak, M., J. Mol. Biol. 196: 947-950 (1987) is appropriately located in the vector portion of the construct.

The 3′ primer has the sequence 5′ cgc GGA TCC CTG AAG AGG CGG GGG TCA 3′ (SEQ ID NO:12) containing the underlined Asp 718 restriction followed by nucleotides complementary to 18 nucleotides of non-coding sequence set out in FIG. 1 (SEQ ID NO:1), including the stop codon.

The amplified fragment is isolated from a 1% agarose gel using a commercially available kit (“Geneclean,” BIO 101 Inc., La Jolla, Calif.). The fragment then is digested with BamH1 and Asp718 and again is purified on a 1% agarose gel. This fragment is designated herein F2.

The vector pA2 is used to express the Cystatin F protein in the baculovirus expression system, using standard methods, such as those described in Summers et al, A MANUAL OF METHODS FOR BACULOVIRUS VECTORS AND INSECT CELL CULTURE PROCEDURES, Texas Agricultural Experimental Station Bulletin No. 1555 (1987). This expression vector contains the strong polyhedrin promoter of the Autographa californica nuclear polyhedrosis virus (AcMNPV) followed by convenient restriction sites. The signal peptide of AcMNPV gp67, including the N-terminal methionine, is located just upstream of a BamH1 site. The polyadenylation site of the simian virus 40 (“SV40”) is used for efficient polyadenylation. For an easy selection of recombinant virus the beta-galactosidase gene from E. coli is inserted in the same orientation as the polyhedrin promoter and is followed by the polyadenylation signal of the polyhedrin gene. The polyhedrin sequences are flanked at both sides by viral sequences for cell-mediated homologous recombination with wild-type viral DNA to generate viable virus that express the cloned polynucleotide.

Many other baculovirus vectors could be used in place of pA2-GP, such as pAc373, pVL941 and pAcIM1 provided, as those of skill readily will appreciate, that construction provides appropriately located signals for transcription, translation, trafficking and the like, such as an in-frame AUG and a signal peptide, as required. Such vectors are described in Luckow et al., Virology 170: 31-39, among others.

The plasmid is digested with the restriction enzymes Bam HI and Asp718 and then is dephosphorylated using calf intestinal phosphatase, using routine procedures known in the art. The DNA is then isolated from a 1% agarose gel using a commercially available kit (“Geneclean” BIO 101 Inc., La Jolla, Calif.). This vector DNA is designated herein “V2”.

Fragment F2 and the dephosphorylated plasmid V2 are ligated together with T4 DNA ligase. E. coli HB101 cells are transformed with ligation mix and spread on culture plates. Bacteria are identified that contain the plasmid with the human Cystatin F gene by digesting DNA from individual colonies using Bam HI and Asp718 and then analyzing the digestion product by gel electrophoresis. The sequence of the cloned fragment is confirmed by DNA sequencing. This plasmid is designated herein pBacCystatin F.

5 mg of the plasmid pBacCystatin F is co-transfected with 1.0 mg of a commercially available linearized baculovirus DNA (“BaculoGold™ baculovirus DNA”, Pharmingen, San Diego, Calif.), using the lipofection method described by Felgner et al., Proc. Natl. Acad. Sci. USA 84: 7413-7417 (1987). 1 mg of BaculoGold virus DNA and 5 mg of the plasmid pBacCystatin F are mixed in a sterile well of a microtiter plate containing 50 ml of serum free Grace's medium (Life Technologies Inc., Gaithersburg, Md.). Afterwards 10 ml Lipofectin plus 90 ml Grace's medium are added, mixed, and incubated for 15 minutes at room temperature. Then the transfection mixture is added drop-wise to Sf9 insect cells (ATCC CRL 1711) seeded in a 35 mm tissue culture plate with 1 ml Grace's medium without serum. The plate is rocked back and forth to mix the newly added solution. The plate is then incubated for 5 hours at 27 degrees C. After 5 hours the transfection solution is removed from the plate and 1 ml of Grace's insect medium supplemented with 10% fetal calf serum is added. The plate is put back into an incubator and cultivation is continued at 27 degrees C. for four days.

After four days the supernatant is collected and a plaque assay is performed, as described by Summers and Smith, cited above. An agarose gel with “Blue Gal” (Life Technologies Inc., Gaithersburg) is used to allow easy identification and isolation of gal-expressing clones, which produce blue-stained plaques. (A detailed description of a “plaque assay” of this type can also be found in the user's guide for insect cell culture and baculovirology distributed by Life Technologies Inc., Gaithersburg, page 9-10).

Four days after serial dilution, the virus is added to the cells. After appropriate incubation, blue stained plaques are picked with the tip of an Eppendorf pipette. The agar containing the recombinant viruses is then resuspended in an Eppendorf tube containing 200 ml of Grace's medium. The agar is removed by a brief centrifugation and the supernatant containing the recombinant baculovirus is used to infect Sf9 cells seeded in 35 mm dishes. Four days later the supernatants of these culture dishes are harvested and then they are stored at 4 degrees C. A clone containing properly inserted Cystatin F is identified by DNA analysis including restriction mapping and sequencing. This is designated herein as V-Cystatin F.

Sf9 cells are grown in Grace's medium supplemented with 10% heat-inactivated FBS. The cells are infected with the recombinant baculovirus V-Cystatin F at a multiplicity of infection (“MOI”) of about 2 (about 1 to about 3). Six hours later the medium is removed and is replaced with SF900 II medium minus methionine and cysteine (available from Life Technologies Inc., Gaithersburg). 42 hours later, 5 mCi of 35S-methionine and 5 mCi 35S cysteine (available from Amersham) are added. The cells are further incubated for 16 hours and then they are harvested by centrifugation, lysed and the labeled proteins are visualized by SDS-PAGE and autoradiography.

Expression of the cDNA sequence encoding the full length human Cystatin F protein, essentially as described in this Example, produced a secreted, mature form of the protein having an N-terminal amino acid sequence (determined directly from the protein by routine microsequencing methods) beginning with amino acid 20 in FIG. 1 (or amino acid number +1 in SEQ ID NO:2), thus indicating that the actual leader sequence consists of the first 19 amino acids shown in FIG. 1 (or amino acids −1 to −19 SEQ ID NO:2).

Example 3 Expression of Cystatin F in COS Cells

The expression plasmid, Cystatin F HA, is made by cloning a cDNA encoding Cystatin F into the expression vector pcDNAI/Amp (which can be obtained from Invitrogen, Inc.).

The expression vector pcDNAI/amp contains: (1) an E. coli origin of replication effective for propagation in E. coli and other prokaryotic cell; (2) an ampicillin resistance gene for selection of plasmid-containing prokaryotic cells; (3) an SV40 origin of replication for propagation in eukaryotic cells; (4) a CMV promoter, a polylinker, an SV40 intron, and a polyadenylation signal arranged so that a cDNA conveniently can be placed under expression control of the CMV promoter and operably linked to the SV40 intron and the polyadenylation signal by means of restriction sites in the polylinker.

A DNA fragment encoding the entire Cystatin F precursor and a HA tag fused in frame to its 3′ end is cloned into the polylinker region of the vector so that recombinant protein expression is directed by the CMV promoter. The HA tag corresponds to an epitope derived from the influenza hemagglutinin protein described by Wilson et al., Cell 37: 767 (1984). The fusion of the HA tag to the target protein allows easy detection of the recombinant protein with an antibody that recognizes the HA epitope.

The plasmid construction strategy is as follows. The Cystatin F cDNA of the deposit clone is amplified using primers that contained convenient restriction sites, much as described above regarding the construction of expression vectors for expression of Cystatin F in E. coli and S. fugiperda.

To facilitate detection, purification and characterization of the expressed Cystatin F, one of the primers contains a hemagglutinin tag (“HA tag”) as described above. Suitable primers include that following, which are used in this example. The 5′ primer, containing the underlined Bam HI site, an ATG start codon and 4 codons thereafter, has the following sequence, 5′ CGC GGA TCC GCC ATC ATG CGA GCG GCT GGA 3′ (SEQ ID NO:13).

The 3′ primer, containing the underlined Xba I site, stop codon, hexa-histidine tag and 15 bp complementary to the 3′ coding sequence (at the 3′ end) has the following sequence, 5′ cgc TCT AGA tca AGC GTA GTC TGG GAC GTC GTA TGG GTA gtg aca acg gag gac 3′ (SEQ ID NO:14).

The PCR amplified DNA fragment and the vector, pcDNAI/Amp, are digested with and then ligated. The ligation mixture is transformed into E. coli strain SURE (Stratagene Cloning Systems, La Jolla, Calif.) the transformed culture is plated on ampicillin media plates which then are incubated to allow growth of ampicillin resistant colonies. Plasmid DNA is isolated from resistant colonies and examined by restriction analysis and gel sizing for the presence of the Cystatin F-encoding fragment.

For expression of recombinant Cystatin F, COS cells are transfected with an expression vector, as described above, using DEAE-DEXTRAN, as described, for instance, in Sambrook et al., MOLECULAR CLONING: A LABORATORY MANUAL, Cold Spring Laboratory Press, Cold Spring Harbor, N.Y. (1989).

Cells are incubated under conditions for expression of Cystatin F by the vector.

Expression of the Cystatin F HA fusion protein is detected by radiolabelling and immunoprecipitation, using methods described in, for example Harlow et al.,. ANTIBODIES: A LABORATORY MANUAL, 2nd Ed.; Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. (1988). To this end, two days after transfection, the cells are labeled by incubation in media containing 35S-cysteine for 8 hours. The cells and the media are collected, and the cells are washed and the lysed with detergent-containing RIPA buffer: 150 mM NaCl, 1% NP-40, 0.1% SDS, 1% NP-40, 0.5% DOC, 50 mM TRIS, pH 7.5, as described by Wilson et al. cited above. Proteins are precipitated from the cell lysate and from the culture media using an HA-specific monoclonal antibody. The precipitated proteins then are analyzed by SDS-PAGE gels and autoradiography. An expression product of the expected size is seen in the cell lysate.

Example 4 Tissue Distribution of Cystatin F Expression

Northern blot analysis is carried out to examine the levels of expression of Cystatin F in human tissues, using methods described by, among others, Sambrook et al, cited above. Total cellular RNA samples are isolated with RNAzol B system (Biotecx Laboratories, Inc. 6023 South Loop East, Houston, Tex. 77033).

About 10 mg of Total RNA is isolated from tissue samples. The RNA is size resolved by electrophoresis through a 1% agarose gel under strongly denaturing conditions. RNA is blotted from the gel onto a nylon filter, and the filter then is prepared for hybridization to a detectably labeled polynucleotide probe.

As a probe to detect mRNA that encodes Cystatin F, the antisense strand of the coding region of the cDNA insert in the deposited clone is labeled to a high specific activity. The cDNA is labeled by primer extension, using the Prime-It kit, available from Stratagene. The reaction is carried out using 50 ng of the cDNA, following the standard reaction protocol as recommended by the supplier. The labeled polynucleotide is purified away from other labeled reaction components by column chromatography using a Select-G-50 column, obtained from 5-Prime −3-Prime, Inc. of 5603 Arapahoe Road, Boulder, Colo. 80303.

The labeled probe is hybridized to the filter, at a concentration of 1,000,000 cpm/ml, in a small volume of 7% SDS, 0.5 M NaPO4, pH 7.4 at 65 degrees C., overnight.

Thereafter the probe solution is drained and the filter is washed twice at room temperature and twice at 60 degrees C. with 0.5× SSC, 0.1% SDS. The filter then is dried and exposed to film at −70 degrees C. overnight with an intensifying screen.

Northern blot analyses conducted essentially as described in this Example showed that expression of Cystatin F mRNA is highly lymphoid tissue specific and is highly expressed in apoptotic or anergic or activated T cells, indicating involvement of Cystatin F in T cell activation-induced apoptosis. In particular, cystatin mRNA is highly expressed in human spleen, peripheral blood lymphocytes (PBL), moderately expressed in thymus, small intestine, heart, placenta, and lung, and expressed at a low level in prostate, ovary, colon, liver, skeletal muscle and pancreas.

Example 5 Gene Therapeutic Expression of Human Cystatin F

Fibroblasts are obtained from a subject by skin biopsy. The resulting tissue is placed in tissue-culture medium and separated into small pieces. Small chunks of the tissue are placed on a wet surface of a tissue culture flask, approximately ten pieces are placed in each flask. The flask is turned upside down, closed tight and left at room temperature overnight. After 24 hours at room temperature, the flask is inverted—the chunks of tissue remain fixed to the bottom of the flask—and fresh media is added (e.g., Ham's F12 media, with 10% FBS, penicillin and streptomycin). The tissue is then incubated at 37 degrees C. for approximately one week. At this time, fresh media is added and subsequently changed every several days. After an additional two weeks in culture, a monolayer of fibroblasts emerges. The monolayer is trypsinized and scaled into larger flasks.

A vector for gene therapy is digested with restriction enzymes for cloning a fragment to be expressed. The digested vector is treated with calf intestinal phosphatase to prevent self-ligation. The dephosphorylated, linear vector is fractionated on an agarose gel and purified.

Cystatin F cDNA capable of expressing active Cystatin F, is isolated. The ends of the fragment are modified, if necessary, for cloning into the vector. For instance, 5″ overhanging may be treated with DNA polymerase to create blunt ends. 3′ overhanging ends may be removed using S1 nuclease. Linkers may be ligated to blunt ends with T4 DNA ligase.

Equal quantities of the Moloney murine leukemia virus linear backbone and the Cystatin F fragment are mixed together and joined using T4 DNA ligase. The ligation mixture is used to transform E. Coli and the bacteria are then plated onto agar-containing kanamycin. Kanamycin phenotype and restriction analysis confirm that the vector has the properly inserted gene.

Packaging cells are grown in tissue culture to confluent density in Dulbecco's Modified Eagles Medium (DMEM) with 10% calf serum (CS), penicillin and streptomycin. The vector containing the Cystatin F gene is introduced into the packaging cells by standard techniques. Infectious viral particles containing the Cystatin F gene are collected from the packaging cells, which now are called producer cells.

Fresh media is added to the producer cells, and after an appropriate incubation period media is harvested from the plates of confluent producer cells. The media, containing the infectious viral particles, is filtered through a Millipore filter to remove detached producer cells. The filtered media then is used to infect fibroblast cells. Media is removed from a sub-confluent plate of fibroblasts and quickly replaced with the filtered media. Polybrene (Aldrich) may be included in the media to facilitate transduction. After appropriate incubation, the media is removed and replaced with fresh media. If the titer of virus is high, then virtually all fibroblasts will be infected and no selection is required. If the titer is low, then it is necessary to use a retroviral vector that has a selectable marker, such as neo or his, to select out transduced cells for expansion.

Engineered fibroblasts then may be injected into rats, either alone or after having been grown to confluence on microcarrier beads, such as cytodex 3 beads. The injected fibroblasts produce Cystatin F product, and the biological actions of the protein are conveyed to the host.

Example 6 Expression of Recombinant Cystatin F in CHO Cells

The vector pC1 is used for the expression of Cystatin F protein. Plasmid pC1 is a derivative of the plasmid pSV2-DHFR (ATCC Accession No. 37146). Both plasmids contain the mouse DHFR gene under control of the SV40 early promoter. Chinese hamster ovary- or other cells lacking dihydrofolate activity that are transfected with these plasmids can be selected by growing the cells in a selective medium (alpha minus MEM, Lift Technologies) supplemented with the chemotherapeutic agent methotrexate. The amplification of the DHFR genes in cells resistant to methotrexate (MTX) has been well documented (see, e.g., Alt, F. W., Kellems, R. M., Bertino, J. R., and Schimke, R. T., 1978, J. Biol. Chem. 253:1357-1370, Hamlin, J. L. and Ma, C. 1990, Biochem. et Biophys. Acta, 1097:107-143, Page, M. J. and Sydenham, M. A. 1991, Biotechnology Vol. 9:64-68). Cells grown in increasing concentrations of MTX develop resistance to the drug by overproducing the target enzyme, DHFR, as a result of amplification of the DHFR gene. If a second gene is linked to the DHFR gene it is usually co-amplified and over-expressed. It is state of the art to develop cell lines carrying more than 1,000 copies of the genes. Subsequently, when the methotrexate is withdrawn, cell lines contain the amplified gene integrated into the chromosome(s).

Plasmid pC1 contains for the expression of the gene of interest a strong promoter of the long terminal repeat (LTR) of the Rouse Sarcoma Virus (Cullen, et al., Molecular and Cellular Biology, March 1985, 438-4470) plus a fragment isolated from the enhancer of the immediate early gene of human cytomegalovirus (CMV) (Boshart et al., Cell 41:521-530, 1985). Downstream of the promoter are the following single restriction enzyme cleavage sites that allow the integration of the genes: BamHI, Pvull, and Nrul. Behind these cloning sites the plasmid contains translational stop codons in all three reading frames followed by the 3′ intron and the polyadenylation site of the rat preproinsulin gene. Other high efficient promoters can also be used for the expression, e.g., the human β-actin promoter, the SV40 early or late promoters or the long terminal repeats from other retroviruses, e.g., HIV and HTLVI. For the polyadenylation of the mRNA other signals, e.g., from the human growth hormone or globin genes can be used as well.

Stable cell lines carrying a gene of interest integrated into the chromosome can also be selected upon co-transfection with a selectable marker such as gpt, G418 or hygromycin. It is advantageous to use more than one selectable marker in the beginning, e.g. G418 plus methotrexate.

The plasmid pC1 is digested with the restriction enzyme BamHI and then dephosphorylated using calf intestinal phosphatase by procedures known in the art. The vector is then isolated from a 1% agarose gel.

The cDNA sequence of the deposited clone is amplified using PCR oligonucleotide primers corresponding to the 5′ and 3′ sequences of the gene:

The 5′ primer has the sequence 5′ CGC GGA TCC GCC ATC ATG CGA GCG GCT GGA 3′ (SEQ ID NO:15) containing the underlined Bam HI restriction enzyme site followed by 6 bases resembling an efficient Kozak sequence plus 15 bases of the sequence of Cystatin F of FIG. 1 (SEQ ID NO:1). Inserted into an expression vector, as described below, the 5′ end of the amplified fragment encoding human Cystatin F provides an efficient signal peptide. An efficient signal for initiation of translation in eukaryotic cells, as described by Kozak, M., J. Mol. Biol. 196: 947-950 (1987) is appropriately located in the vector portion of the construct. The 3′ primer has the sequence 5′ cgc GGA TCC CTG AAG AGG CGG GGG TCA 3′ (SEQ ID NO:16) containing the underlined Asp718 restriction followed by nucleotides complementary to 18 nucleotides of non-coding sequence set out in FIG. 1 (SEQ ID NO:1), including the stop codon.

The amplified fragments are isolated from a 1% agarose gel as described above and then digested with the endonuclease BamHI and then purified again on a 1% agarose gel.

The isolated fragment and the dephosphorylated vector are then ligated with T4 DNA ligase. E. coli HB101 cells are then transformed and bacteria identified that contained the plasmid pC1 inserted in the correct orientation using the restriction enzyme BamHI. The sequence of the inserted gene is confirmed by DNA sequencing.

Transfection of CHO-DHFR-Cells

Chinese hamster ovary cells lacking an active DHFR enzyme are used for transfection. 5 mg of the expression plasmid Cl are cotransfected with 0.5 mg of the plasmid pSVneo using the lipofectin method (Felgner et al., supra). The plasmid pSV2-neo contains a dominant selectable marker, the gene neo from Tn5 encoding an enzyme that confers resistance to a group of antibiotics including G418. The cells are seeded in alpha minus MEM supplemented with 1 mg/ml G418. After 2 days, the cells are trypsinized and seeded in hybridoma cloning plates (Greiner, Germany) and cultivated from 10-14 days. After this period, single clones are trypsinized and then seeded in 6-well petri dishes using different concentrations of methotrexate (25, 50 nm, 100 nm, 200 nm, 400 nm). Clones growing at the highest concentrations of methotrexate are then transferred to new 6-well plates containing even higher concentrations of methotrexate (500 nM, 1 mM, 2 mM, 5 mM). The same procedure is repeated until clones grow at a concentration of 100 mM.

The expression of the desired gene product is analyzed by Western blot analysis and SDS-PAGE.

Example 7 Protease Inhibition by Recombinant Cystatin F

Cystatin F protein produced in a baculovirus system, essentially as described in Example 2, above, was found to inhibit papain reversibly with K_(i)(app)=1.23 nM. +/−0.31 (n=5). (K_(i)(app) indicates an apparent K_(i) which has not been adjusted for the competing effects of the substrate in the assay; the true K_(i) value is somewhat lower than the K_(i)(app) value.) This K_(i)(app) is sufficient to allow titration of papain using methods known in the art, indicating that the recombinant protein is at least 50% active. Compensated for substrate competition K_(m)=60 μM), the true K_(i)=1.05 +/−0.27 nM. For cathepsin B, the K_(i)(app) value is much greater than 1000 nM, indicating that Cystatin F is not a cathepsin B inhibitor. For Cruzipain (from Trypansoma cruzi), K_(i)(app)=9.7 nM. Thus, Cystatin F is a cysteine protease inhibitor similar to cystatin D in inhibition profile.

It will be clear that the invention may be practiced otherwise than as particularly described in the foregoing description and examples.

Numerous modifications and variations of the present invention are possible in light of the above teachings and, therefore, are within the scope of the appended claims. 

1. An isolated polynucleotide comprising a polynucleotide having at least a 70% identity to a member selected from the group consisting of: (a) a polynucleotide encoding a polypeptide comprising an amino acid sequence as set forth in SEQ ID NO:2; (b) a polynucleotide encoding a polypeptide comprising amino acid 19 to amino acid 145 as set forth in SEQ ID NO:2; (c) a polynucleotide which is complementary to the polynucleotide of (a) or (b); and (d) a polynucleotide comprising at least 15 bases of SEQ ID NO:1.
 2. The polynucleotide of claim 1 wherein the polynucleotide is DNA.
 3. The polynucleotide of claim 1 wherein the polynucleotide is RNA.
 4. The polynucleotide of claim 1 wherein the polynucleotide is genomic DNA.
 5. The polynucleotide of claim 2 which encodes the polypeptide comprising amino acid 1 to 145 of SEQ ID NO:2.
 6. The polynucleotide of claim 2 which encodes the polypeptide comprising amino acid 19 to 145 of SEQ ID NO:2.
 7. An isolated polynucleotide comprising a polynucleotide having at least a 70% identity to a member selected from the group consisting of: (a) a polynucleotide which encodes a mature polypeptide having the amino acid sequence expressed by the human cDNA contained in ATCC Deposit No. 97463; (b) a polynucleotide which is complementary to the polynucleotide of (a); and (c) a polynucleotide comprising at least 15 bases of the polynucleotide of either (a) or (b).
 8. The polynucleotide of claim 1 comprising the sequence as set forth in SEQ ID NO:1 from nucleotide 1 to nucleotide
 633. 9. The polynucleotide of claim 1 comprising the sequence as set forth in SEQ ID NO:1 from nucleotide 112 to nucleotide
 633. 10. A vector comprising the DNA of claim
 2. 11. A host cell comprising the vector of claim
 10. 12. A process for producing a polypeptide comprising: expressing from the host cell of claim 11 the polypeptide encoded by said DNA.
 13. A process for producing a cell which expresses a polypeptide comprising genetically engineering a cell with the vector of claim
 10. 14. A polypeptide comprising a member selected from the group consisting of: (a) a polypeptide having an amino acid sequence set forth in SEQ ID NO:2; (b) a polypeptide comprising amino acid 19 to 145 of SEQ ID NO:2; and (c) a polypeptide which is at least 70% identical to the polypeptide of either (a) or (b).
 15. The polypeptide of claim 14 wherein the polypeptide comprises amino acid 1 to amino acid 145 of SEQ ID NO:2.
 16. The polypeptide of claim 14 wherein the polypeptide comprises amino acid 19 to amino acid 145 of SEQ ID NO:2.
 17. A compound which inhibits activation of the polypeptide of claim
 14. 18. A compound which activates the polypeptide of claim
 14. 19. A method for the treatment of a patient having need of Cystatin F comprising administering to the patient a therapeutically effective amount of the polypeptide of claim
 14. 20. The method of claim 19 wherein said therapeutically effective amount of the polypeptide is administered by providing to the patient DNA encoding said polypeptide and expressing said polypeptide in vivo.
 21. A method for the treatment of a patient having need to inhibit a Cystatin F polypeptide comprising administering to the patient a therapeutically effective amount of the compound of claim
 17. 22. A process for diagnosing a disease or a susceptibility to a disease related to an under-expression of the polypeptide of claim 14 comprising determining a mutation in a nucleic acid sequence encoding said polypeptide.
 23. A diagnostic process comprising analyzing for the presence of the polypeptide of claim 14 in a sample derived from a host.
 24. A method for identifying compounds which bind to and inhibit activation of the polypeptide of claim 14 comprising: (a) contacting a cell expressing on the surface thereof a receptor for the polypeptide, said receptor being associated with a second component capable of providing a detectable signal in response to the binding of a compound to said receptor, with an analytically detectable Cystatin F polypeptide and a compound under conditions to permit binding to the receptor; and (b) determining whether the compound binds to and inhibits the receptor by detecting the absence of a signal generated from the interaction of the Cystatin F with the receptor. 